Taliesin D&D

 

In essence: how little would I need to change about D&D to make it playable for me?

 

Stats

 

Roll 3d6 for stats.

 

Low stats increase Feature points and Saves. 

 

Three of your stats (Strength, Charisma, and Intelligence) impact Saving Throw, but the other three (Wisdom, Constitution, and Dexterity) affect Features.

 

3 - +4

4-5 - +3

6-8 - +2

9-10 - +1 

 

So Cha 9, Dex 14, and Wis 6 give you a Saving Throw of +3, and Str 5, Con 11, and Int 10 give you 4 Feature Points.

 

(Alternately, each "+1" gives you a die to roll. Roll them all; high results mean you get a Feature point, and low results mean you get a Save bonus.)

 

Optionally, if you have a basic mechanic where Ability Scores are not so important, but lightly modify d20 rolls, you can have a Fate score which modifies Saving Throws.

 

Every character has a basic Saving Throw, but can also accumulate Saving Throw Bonuses (Will, Reflex, Fortitude, Magic Resistance, Poison, etc.) depending on class and/or Features.

 

If you need stat modifiers, I like:

 

Moldvay/Basic

3 -3

4-5 -2

6-8 -1

9-12 0

13-15 +1

16-17 +2

18 +3

 

Or, my own

3-5 / 3-4         -2     

6-8 / 5-7         -1     

9-11 / 8-10      0     

12-14 / 11-13  +1 

15-17 / 14-16  +2

18 / 17-18        +3

 

These modifiers can also work as Feature Points modifiers.

 

I'd almost certainly rename the stats, as well.

 

Might (Strength)

Grace (Dexterity)

Bearing (Charisma)

Lore/Arcane (Intelligence)

Instinct/Cunning (Wisdom)

Fortitude (Constitution)

 

(Saves: Lore, Bearing, Might - FPs: Grace, Instinct, Fortitude)

 

The most minor mod would be to rename Int and Wis: Lore and Cunning would be great (or just rename Wisdom to Instinct/Cunning)!

 

The "Luck" stat is your Saving Throw. Use it for all kinds of things! Could call it "Fate", which would be cool.

 

 

Features & Questionnaire

 

See Kroll. Includes equipment and money. (Default character is broke.)

 

No clerics; being "blessed" and being able to "lay on hands" is a Feature.

 

Features should be written in a table which matches a deck of cards. Each player draws two Features cards, discarding and re-drawing anything s/he can't afford. Once that's done, you *must* buy at least one. Discard and then draw again; continue until all Feature points have been spent. This also guarantees no two characters have the same Features.

 

Make sure to include lots of 1-pt Features.

 

(It would of course be great to actually write the Features on cards and assemble a deck that way.)

 

 

Class

 

Adventurer is default. (Or call it "Vagabond".)

 

Warrior requires an 11+ in Strength/Might.

Arcanist requires an 11+ in Intelligence/Arcane/Learned/Lore.

 

Everyone levels up at the same rate, unless you have specialty classes.

 

With good stats, you have special classes too:

 

* Elf (Int 12, Cha 9?) Cha/Int or Fate?

* Hobbit (Dex 12, Con 9?) Dex/Wis(Instinct)

* Dwarf (Con 12, Wis 9?) Con/Str

 

(Roughly one in 8 characters rolled qualify for a special class.)

 

Elf is all about magic and fighting, weird magic abilities. Fighting doesn't have to be too good! Levels slowly.

Magic could be limited by virtue of having a weaker spell list than Arcanists, if that makes sense (depends on how you get new spells, essentially).

 

Hobbits are all about being the underdog and getting out of the way when necessary. Bonus die to attempts to hide! Large creatures have trouble hitting them. Good with missile weapons, good saving throws. Can't carry much stuff and limited in use of horses and equipment. Level up only slightly more slowly.

 

Dwarves are all about being sturdy and tough. They can carry more, they have more hit points (1d10?) and really good saving throws. Not necessarily *quite* as good as a Warrior at fighting. Maybe some underground/stonework special ability (like a bonus die!), as well as for appraising value of stuff. Level faster than Elf, slower than Hobbit.

 

If using Professions:

 

* Elves are naturally gifted Rangers. (And good Will save!) "Wilderness Lore"

* Hobbits are naturally gifted Scoundrels. (And good Reflex save!) "Street Smarts"

* Dwarves are naturally gifted Tinkers. (And good Fortitude save!) "Craft"

(Sage?)

 

This is probably best represented by a bonus die.

 

They start as 2d6+adds, with +0 as default? Rolling a 10+ is equivalent to typical 1 in 6 D&D checks.

 

A first-level Adventurer could choose to add +1 to two of the last three by choice, or (more likely), those would be Features.

 

Or they could be rated in dice: d4, d6, d8, d10, d12

  

All should level up a little slower than standard classes.

 

 

Levels

 

The game is designed to span 10 levels, plain and simple.

 

 

Hit Points and Damage

 

The basic principle: a person has d6 hit points. An attack does d6 damage.

 

Scrawny or weak things have d4 hit points. Frightening or monstrous things have d8 hit points.

 

A PC has a hit point pool, consisting of a d6 for being human, plus a Constitution die (d4 by default) and a class die (d6 Adventurer, d4 Arcanist, d8 Warrior).

 

When you get hit, roll your hit point pool. If you survive, write down your remaining total. 5 hit points or more returns to quantum health after a rest/healing.

 

Each level, add one class die to your pool. You cannot have more than three dice of any one type - additional dice get upgraded to the next best type.

 

At level 4, you drop your highest die instead of getting a new die... but now you can keep 2!

 

At level 8, you drop your highest die instead of getting a new die... but now you can keep 3!

 

(The rule is that you can drop your highest die instead of getting a new one, and this allows you to keep one more die. However, you may only keep one die for every two dice remaining in your pool, so to keep two you must have four, and to keep three you must have six. This generates the three tiers described above.)

 

Another variation is that you roll a "death save" against the incoming damage (rolling your hit point pool, again). If you beat it, you live. If you match it, you're unconscious. Write down the damage you take in a running total. When you heal or rest, you get to halve this total (rounding down). These two approaches are mathematically identical (but one involved more rolling).

 

How do you die?

 

Incapacitated: roll vs. Death (The incoming damage is equal to your remaining hit points or greater by one)

* Success, you are knocked unconscious.

* Failure, you have a critical wound, and you will die without care.

 

Dead: roll vs. Death (The incoming damage is greater than your remaining hit points by two points)

* Success, you have been horrificly maimed, but you will survive with care.

* Failure, you're a goner.

 

Or Constitution check?

 

In any case, you cannot keep fighting.

 

HP Chance of survival Chance of Incapacitation Chance of Death

6               5/6                1/6                        0/6

5               4/6                2/6                        0/6

4               3/6                2/6                        1/6

3               2/6                2/6                        2/6

2               1/6                2/6                        3/6

1               0/6                2/6                        4/6

 

Eero's rules on 0 hp or less is: roll Con - negative HP total for unconsciousness. (On a failure, you're dead or dying.)

 

Not bad!

 

Ideally a "recover"-type move would be invoked after the fight, if the body could be found (or comes to on his/her own). Then death is always uncertain. The person finding the body rolls for it, or that player can roll for it themselves, but with a penalty.

 

 

Basic Guidelines for Hit Points and Damage

 

HP is based on body size and resilience. However, PCs get HP increases by virtue of experience as a special thing.

 

Optionally, some NPCs may get more HP as well. (But their HP should be also determined fictionally, like "2d6 HP, combat prowess", or "1d6 HP, magical defensive spells", so that they can be circumvented.)

 

Normal humans have d6 hit dice. Monsters and supernatural things have d8 hit dice, and a to-hit/save bonus of +1/hit die.

 

So this means a 1 HD Orc is equivalent to a strong and skilled warrior. I like this.

 

Damage is usually 1d6, likely to kill anything in one blow except for the most mighty of monsters.

 

   [1d3-1 - a weak, ineffectual attack, like pummeling someone]

   [1d3 - hitting someone with a rock in your fist, or with a chair, improvised weapons]

 [1d4 - light weapons]

1d6 - most weapons

 [1d8 - heavy, two-handed weapons]

2d6 - scary shit, like a ballista bolt or a small explosion

3d6 - unthinkable stuff like dragon breath or a large explosion

 

So a character has to get a few levels before s/he can withstand "serious scary shit" reliably. Only a top-level hero can reliably survive unthinkable catastrophic damage. (Under the hit point pool system, that is, where you only get a second hit die at 4th level, and a third at 8th level.)

 

But even a normal person with 1d6 hit points can survive a deadly fall (3d6).

 

That's our scale here.

 

Encumbrance

 

Strength determines how much you can wield/carry. (Important!)

 

* You must be using a normal (not small) weapon to benefit from a Strength damage bonus of +1.

* You must be using a heavy weapon to benefit from your full Strength bonus. 

 

Low Strength just limits what you can use (or force a hit penalty if you're using too heavy).

 

Some spitballing:

 

Strength and carrying

4 - just a light weapon, encumbered in anything

7 - light armour and regular weapon, no encumbrance though

10 - light armour and heavy weapon, or encumbrance, light armour, and normal weapon, or medium armour and normal weapon

13 - medium armour, heavy weapon, and encumbrance, or heavy armour and regular weapon and encumbrance

16 - heavy armour, heavy weapon, and encumbrance

18 - all that and HEAVY encumbrance

 

(Test:

Enc - 5

Crazy Enc - 8

Light weapon, none

Normal weapon - 2

Heavy weapon - 5

Light armour - 2

Medium armour - 5

Heavy armour - 8

Shield - 4

 

Or, one point per:

* Encumbrance (1) like a heavy backpack (or 5+ items)

* Heavy encumbrance (2) like a heavy backpack with a tent strapped to it, or full of gold (or 10+ items)

* Normal weapon (1)

* Heavy weapon (2)

* Light armour (1)

* Medium armour (2)

* Heavy armour (3)

* Shield (1)

 

People have 4 slots, modified by their Str mod.

 

3   1

4   2

5   2

7   3

10  4

13  5

16  6

18  7

 

Armour is:

 

Slapdash, makeshift, cheap, primitive (DR 1)

Military, metal, medium, chain, quality - infantry (DR 2)

Heavy, plate, rare, expensive - cavalry (DR 3)

 

Same for shields; but they also have a size (buckler, 2, infantry shield, 3, tower shield, 4), which is how often they stop an attack.

 

A shield breaks if it is used to defend against any attack which deals 5+ damage!

 

A last way:

 

You can carry as much weight in stone (14 lbs) as your Might die before you're heavily encumbered. (Makes it hard to do anything but walk.)

 

* - Might die varies from null to d10. So a typical character can carry up to 6 stone before being encumbered.

 

10 stone - a person

4 stone - plate mail

2 - chain mail, tower shield, massive weapon, etc.

1 - leather armour, most weapons, set of 8 torches, shield, rations for four days, 300 coins, full helm

1/4 stone - helmet, sheathed sword, spear, bow, quiver of arrows (36), lantern, wineskin, 2 toches, iron spikes, coil of rope (30 ft)

 

Don't bother tracking little stuff.

 

If you have more than half of your Might die, you're encumbered, which means you run slower and have trouble climbing or being sneaky.

 

You can carry up to twice your Might die before you have to make rolls to move.

 

Someone without Might has a load of 2.

 

Unencumbered     < 1/2 Might die

Encumbered             up to Might die

Heavily Encumbered   > Might die

Limit        2x Might die

 

An Encumbered character moves at half the rate of other characters, and cannot move quietly or climb things. (Perhaps with penalties under very limited circumstances.)

 

 

Healing

 

One hit point per night, with regaining "quantum" status at 5 HP, works well for me.

 

Alt: Or maybe you roll Constitution, and on a success you get 1 HP back, but on a failure you must stay in bed/rest in order to do so. (So you can choose between going ahead at your current hit points or resting.)

 

Alt: You get one roll for getting a night's rest and food, and one for medical care. If only one succeeds, you've got to make a choice.

 

Other thoughts:

 

* You received first aid after suffering your injuries.

* You have a good meal and some time to rest.

* You have expert medical care.

* You have a good night's sleep.

 

List of conditions and each one grants a Con check to see if you heal one hit point.

 

...

 

Healing works great if you get to roll the amount healed in hit dice! (So wizard heals d4s while fighter heals d8s.)

 

...

 

You keep track of damage taken. 8 hit points of damage!

 

Each time you get hit, you roll your hit dice against the current damage total.

 

When you heal/rest, you erase half of your damage total (round up).

 

If you can't match the current damage total, you die. Doubles for healing, too! Like in Kroll, where you roll hit dice against wound level.

 

Give healing spells to magic-users in the meantime. Healing is worth 1d6 hit points. Or maybe it allows a Con check for diseases and weird shit like that.

 

Character Feature: You're a saint. You are considered blessed by some god. You can lay on hands to heal people.

 

XP

 

You gain 1 XP per silver piece (or equivalent, for treasure).

 

The most XP you can gain at one time is how much you need for the next level. (e.g. 2000 XP)

 

Any excess is wasted. Brilliant rule from Eero!

 

You score XP when you carry a treasure out of a dungeon to safety, and again when you spend treasure for non-adventuring ends.

 

This means you don't have to have quite as much wild treasure hauling!

 

Encountering monsters gives you (small) XP, a la B/X D&D (e.g. 15 XPs for an Orc). You don't need to kill or defeat them.

 

Probably want less XP per level, like 1000. Allows faster leveling AND smaller treasure hauls are still exciting - win-win! If that proves too fast, go back to a default of 2000/level. (And doubles every level, of course. Unless you want 0, 1000, 2000, 4000, 7500, 12500, 20000, 30000, 45000, 70000.)

 

Initiative

 

Each side rolls a d6. If relevant, some people might get their own roll, too.

 

Some advantages give you a bonus die (Instinct, if relevant). In a group, you get to roll your own and decide which to use.

 

Highest roll goes first, difference in results means that many rounds you will have the initiative for, before rerolling.

 

On a tie, you don't have enough time to control exactly what's happening. Decide whether you want to:

 

* Grab the initiative, throwing yourself into the chaos of melee!

 

or

 

* Cede the initiative, choosing where to make your stand before the enemy strikes.

 

Another way to look at it: declare first (opponents get to react), or let your opponents declare first but act last/react?

 

In this case, initiative lasts for three rounds. (Or until something does to change it, for a reroll. That's generally true in any case!)

 

Surprise: if someone surprises you, you get a Reflex save to see if you can react normally (but automatically lose initiative).

 

 

 

 

 

 

 

 

 

Blackjack Model

 

Roll score or under. 

 

Higher is better.

 

1 is automatic failure. 20 is automatic success.

 

Typical tasks are DC 2.

Challenging tasks are DC 5.

Daunting tasks are DC 8.

 

When you have time, you roll twice.

 

e.g.

 

Str 10	normal	challeng	daunting
fail	25%	42%	64%
mixed	50%	45%	32%
success	25%	12%	4%
one roll	50%	35%	20%
Str 6
fail	49%	72%	90%
mixed	42%	25%	9%
success	9%	2%	1%
one roll	30%	15%	5%

 

 

Stats need to be reworked. Roll 3d6, keep lowest two, and add 6. (Take your highest die and flip it to a 6.)

 

Gives an 8 to 18 range! Not bad. Averages around 12 or so.

 

Another way is to keep normal D&D stats, but use two-roll, AW-style Ability checks. (Only one roll in combat situations.) 

 

If using the Blackjack model and AW-style double rolls, assume that the opposition always rolls a 4. (Or their Prowess/Armor Class, in the case of a monster in combat.)

 

This means you need a 5 to succeed. It sounds like stats would be really low (since below 5, they're all the same), but it just means that a 3-4 is useless. That's ok! And they're not totally useless: a 9-10% chance of success or so, and about 20% total for someone with a stat of 5.

 

Hit points could follow a AW-move-type system, with one roll to resist harm and another to recover.

 

ThAC0 -

 

You have a "combat skill". It starts at 10 for most people, 11 for adventurers or monsters, or anyone with combat experience. 12 for Fighters.

 

Base Armor Class is 0. Then you add your armor. On top of that, put any bonuses for Dexterity or other "combat reflexes". 

 

This means a "typical" person would be hit on 2-11 and 20 (55% chance), like AC 10 in D&D. 

 

A monster or character with AC 6 would normally be hit on a 13+. AC 4 (plate) would be on a 16+ (25%).

 

Under these rules that would be AC 2, AC 6, AC 8.

 

AC 8 means you hit on a 8-11 and 20: 25%. 

 

So the rule is that D&D armor class is converted to new AC by doing

 

( 12 - armor class )

 

So, armor class 7 becomes AC 5 under this system.

 

 

 

Weirder ideas for Armor Class

 

Armor (base)

 

2 - none

3 - helmet

4 - one limb

5 - half suit

6 - mostly covered, no helmet

7 - full suit of armour

8 - full suit + helmet, gloves, etc.

 

Damage reduction - leather 1, scale or ring 2, chain 3, plate 4, heavy plate 5

Or possibly light armour gives +1 to resist harm roll, heavy armour gives +2 (and it may vary depending on weapon type)

 

Combat Reflexes

 

0 - unmoving, dead

1 - prone, in trouble

2 - regular human

3 - experienced human, adventurer, warrior?

+ Dex bonus or whatever

 

 

 

 

Or if you have a "miss chance" in there:

 

Your ability starts at 14. 

 

Reflexes = 4 for most people.

Armor Class adds to that.

 

So if you're wearing 4 points of armour, 1-4 dodge, 5-8 armor, 9+ hit.

 

It feels a bit weird, but could work.

 

Now we can give better odds of missing, because armor only reduces damage.

 

But we don't want it to fluctuate too much, so as to avoid recalculating in play. Hmmm!

 

So, we want: 1-5 miss, 6-10 armour, 11+ miss (but actually 11-15 hit, 16-19 miss, 20 hit, if 15 is your combat ability)

 

Combat modifiers would be applied to the incoming hit roll, as usual, no recalculation necessary.

 

So you get hit on 6-15. 

 

Light armour, not much coverage: 4 points.

Heavy armour, near complete coverage: 9 points.

Helmet gives +1 armour.

Shield increases your Reflexes.

 

So 1-4 miss, 5-14 (plate mail), 15+ hit

 

Only a 10% chance of getting through the armour! Sounds pretty good, actually.

 

1-7 miss (shield), 8-18 (plate mail).

 

Now no one can get you. Not bad either! (5% chance to get through armour on a 20, of course.) Knock away the shield and:

 

1-4 miss, 5-15 (plate mail), 16+ hit

 

Armour

covers leg (1)

covers leg (1)

covers head (1)

covers arm (1)

covers arm (1)

covers upper torso (2)

covers lower torso (2)

covers face (1)

or: gauntlets/boots (1)

 

for up to ten!

 

Maybe shield could layer in, as well, under the armour:

 

1-4 dodge

5-9 shield + armour

10-14 armour

15+ exposed hit

 

So then the monster rolls to hit you! And shield and armour both have DR, so shield likely blocks whatever/anything.

 

If you full-out attack or whatever, you can't dodge. Reduce dodge by a set number (so it doesn't depend on your skill). You have active dodge and passive dodge, in other words.

 

1-2 passive dodge

3-4 active dodge

 

Conversions:

 

Base miss is 4.

Convert 10 - armor class into points of increased miss and damage reduction, accordingly.

 

So a monster with AC 6 might be 4 points of miss and 2 damage reduction. Default armor coverage is 6?. Or just by ear.

 

1-8 miss, 9-14 DR 2, 15+ hit

 

 

 

Ok, so now we want more hits and also more armour.

 

1. Let's say normal human is AC 10. That's 55% hit, 45% miss.

 

How about: 1-3 miss, 4-13 hit, 20 hit - Reflexes 3, base combat skill 13

 

2. Now someone in leather armour has AC 8, that's normally a 45% hit, 55% miss, no damage reduction.

 

How about: 1-3 miss, 4-11, 12-13 hit, 20 hit - Reflexes 3, armor coverage 8 - that's a 40% hit -2 damage, 15% hit straight up.

 

3. Someone with awesome Dexterity and heavy armour would have AC 2. That's 15% hit, 85% miss. (Although maybe heavy armour should reduce dexterity bonuses?)

 

How about: 1-5 miss, 6-13 hit, 20 hit - Reflexes 5, armor coverage 8 (DR 4) - that's 40% hit -4 damage, 5% hit straight up.

 

Now someone hitting those three cases with combat skill 17 would look like:

 

1. 1-3 miss, 4-17 hit, 20 hit - 75% hit

2. 1-3 miss, 4-11 armour, 12-17 hit, 20 hit - 40% hit -2 damage, 35% hit straight up

3. 1-5 miss, 6-13 armour, 14-17 hit, 20 hit - 40% hit -4 damage, 25% hit straight up

 

 

 

I worked out elsewhere that if your attacks deal 1d6 damage and your odds of hitting are roughly 50/50, then one level of "armor class" is equal to one level of "damage reduction" (so that leather armour equals DR 1). Under this system, you roll to defend yourself:

 

Your defense score is, say, 11. Your armour DR is 1. The monster has a Prowess score - say it's 4. You roll your d20 to defend.

 

1-3 Monster hits doing full damage (3.5*3=10.5)

4-11 You defend!

12-19 Monster hits, armour reduces by one (2.5*8=20)

20 You defend!

 

Expected damage equals: 30.5/20. Against an unarmoured person, exp dmg equals: 38.5 [Difference for one level of DR is 8 points.]

 

In normal D&D, it might look like (monster rolls this time, against leather armour dude with AC 7):

 

1-11 You defend!

12-20 Monster hits (3.5*9=31.5)

 

Against unarmoured person this would be exp dmg 39. [Difference for one level of DR is 7.5 points.]

 

This works great, except you have to keep monster Prowess levels really really tight (or armour becomes useless), maybe no higher than 8. Increase monster damage instead.

 

With Blackjack, it looks like this

 

 

Alignments

 

Probably not, but if you had to...

 

Moral

Good - get XP for treasure recovered (i.e. is rightfully yours), and for people saved (10 XP per commoner saved, 20 XP per noble-born, 50 XP per royal)

Or twice as much for treasure returned to rightful owner?

Neutral - get XP for treasure recovered (then half again when you spend it?)

Evil - get XP for treasure... of any kind, you can steal, extort, kill or murder, for instance

 

Metaphysical

Law (?) - aligned with deities of light and order, obey tradition, follow cosmic tradition

Neutral (most people)

Chaos - aligned with deities of chaos and growth/change, disobey tradition

 

 

Apocalypse World-style

 

Dice pool against a chart replaces d20 rolls; unified mechanics.

 

You could still roll your stats, e.g.:

 

3-6 null      6 FP 

7-9 d4        3 FP

10-12 d6    1 FP

13-15 d8    0 FP

16-18 d10 -2 FP

 

Might - Aragorn - fighting, strength

Instinct - Gollum - dodging stuff, thief skills, reading people (Cunning + that, plus traps and crafts)

Bearing - Gandalf - scholarly magic, charisma, leadership

Fate - Frodo - blood magic, saving throws, luck

Grace - Legolas - running, jumping, climbing (Deftness + that, plus thief skills and dodging)

(Fortitude - Gimli - saving throws, recover, resisting stuff)

 

Deftness/Instinct and Cunning/Grace make clearer pairs.

 

Or simpler:

 

Mighty

Deft

Cunning

Noble

 

Your basic roll is: 1d6 basic die for opposition (can vary under unusual circumstances), your stat, and a circumstance die (d4 by default).

 

2 to 4: disaster

5 to 7: failure

8 to 9: complication (d4 bonus die, if setting up another roll)

10 to 12: success (d6 bonus die)

13 or more: extraordinary (d8 bonus die)

 

Can get rid of hit points and damage this way, just have a combat roll which tells you if the monster's dead.

 

Resist injury and recover rolls for the PCs.

 

May have "Mortality" boxes, which you check and cross off like hit points.

 

Everything else is basically straightforward.

 

 

 

 

On Magic

 

In my preferred view, spells are colourful and historic and always attributed to a particular historical character (e.g. Tenser). They also have particular characters and quirks.

 

The easiest way to do this would be to have a small set of starting spells, and roll from that table when starting a campaign.

 

Subsequently, new spells must be found and/or researched. They will be of unknown quality, and have unknown quirks. 

 

When a spell fails, roll on some sort of table to find out how it goes wrong - that now becomes the spell's character (and may decide or imply the character of other spells from the same grimoire/mage).

 

* Spell goes wildly out of control, overdoing its effect dramatically.

* Spell goes wildly out of control, targeting someone or someplace completely different than intended.

* Spell fizzles and leaves with some of the caster's life force, weakening the caster. (Maybe even hit points? Or stat reduction? Or just casting penalty?)

* Spell takes a bite out of the caster, hit points-wise (but doesn't kill - 0 just means unconscious).

* Spell goes off, but targeting is wonky: it affects someone or somewhere other than intended.

* Spell is weaker than normal, only having half effect.

* The spell's effect is reversed or perverted.

* The spell somehow semi-permanently alters the caster. Growth, shape change, features, scar, etc.

* Kills all plants in the area.

* Violent: gives everyone painful headache (or worse, hit point loss).

* Caster's senses become unreliable for 1d6 rounds.

* Speeds up caster's metabolism: caster heals twice as fast and can run faster, but becomes ravenously hungry.

* Caster is plagued with bizarre visions and nightmares.

* Caster (1-4) or target (5-6) loses memory of current events, disoriented.

* Caster (1-4) or target (5-6) ages 1d6 years.

* Target (1-4) or caster (5-6) is energized and invigorated, gain hit points and/or Strength temporarily.

* The spell opens a dimensional rift, as appropriate to the effect.

* Spell is unsettled: preparing it the next time will require extra effort and time.

* Spell is wild: it will be more likely to misfire next time it is cast. (May be cumulative.)

* Spell grows stronger, but harder to control. (May be cumulative.)

* Spell grows weaker, but easier to control. (May be cumulative.)

* Roll again twice, apply both effects.

 

Afterward, the spell has this effect on any miscast, unless (something) is rolled, for possible secondary effects.

 

Characters probably start with certain Grimoires, which are focused on subjects, and allow research of spells related to that subject. (Which can be narrowed down with 50/50 rolls as the character gets to know the book.)

 

Remember the comments below as well as The Wizard's Grimoire...