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Mechanics for spell failure & consequences

rustydm

First Post
I'm looking for an examples of explicit game mechanics for spell-casting failure and consequences. Dungeon Crawl Classics is the only one I've seen; it has pretty dire outcomes. D&D 5E (and previous editions) assume if you know the spell, it always works perfectly. I'm curious about other fantasy systems, not justd20-based. Thanks.
 

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SavageCole

Punk Rock Warlord
Warhammer Fantasy Roleplay 4e is worth a look for miscast rules, etc. All spells (divine and arcane) require a specific skill check roll and there are miscast tables and consequences (good & bad) for succeeding too well.
 

uzirath

Adventurer
In both GURPS Magic and the Dungeon Fantasy Roleplaying Game (a fantasy-focused GURPS variant), if you critically fail a spell roll, something bad happens. There is a default critical spell failure table that ranges from relatively minor effects like "Spell produces nothing but a distracting sensory effect – flash, moaning, rotten smell, etc. – that advertises caster’s presence (and miserable failure!)" to more serious consequences (e.g., the caster takes injury, summons a demon, or forgets the spell for a week or more). The rules encourage the GM to "improvise instead of using the table, but shouldn't kill the caster outright." A typical beginning caster will critically fail on a 17 or 18 on three dice (just shy of a 2% chance). More advanced casters with higher skill levels might only critically fail on an 18 (0.5%). But, if your effective skill drops, the chances of a critical failure can go up. So a wizard trying something desperate might swallow a lot of penalties and increase their odds of a critical mishap.

In addition, GURPS Thaumatology (one of my favorite books) is all about customizing a magic system to suit your campaign vision. It includes numerous options for changing how successes and failures work with different magical traditions. Of note is Appendix B which includes eight alternate critical failure tables for the standard magic system. Examples include a table for Celtic magic, clerical magic, diabolic magic, illusory magic, etc. If you want to see two worked examples, the preview PDF has a page from the appendix that includes the clerical and comedy tables. I've attached the page to this post.
 

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DMMike

Guide of Modos
I'm looking for an examples of explicit game mechanics for spell-casting failure and consequences. Dungeon Crawl Classics is the only one I've seen; it has pretty dire outcomes. D&D 5E (and previous editions) assume if you know the spell, it always works perfectly. I'm curious about other fantasy systems, not justd20-based. Thanks.
Not entirely true - in D&D the spell failure roll is on the target, not the caster. Typical failures are that a spell does half damage, or nothing at all (ha on you, spell-caster!).

In Modos RPG, the spell failure rules are a little different*:
403Magic Minimum ContestA magic contest result below 1 subjects a magic user to Spell Failure, and the magic actions used up to that point are lost. 002, 003, 011, 402
413Spell FailureWhen a magic contest is 0, a Spell Mishap occurs. A contest of -1 to -4 results in no effect. A contest of -5 to -8 results in no effect, and the caster must pay the MP cost. A contest below -8 causes d8 physical damage to the magic user, the magic user must pay the MP cost, and the GM imposes a harmful effect related to the Power Effect. 002, 003, 011, 402, 403, 404
414Spell MishapAn unfavorable, but minor power effect described by the magic user, with an MP cost of 1, and subject to GM approval. Especially unfavorable spell mishaps can earn a hero point. 000, 114, 404, 407
* It's a modular game, so the GM can use any spell mishap module she wants. Like this one I just made up.
 

uzirath

Adventurer
It's been a while since I've played Dungeon World, but its basic mechanic holds true for spells. Depending on your die roll, you might achieve a total success, a partial success (success with complications), or a failure. In the latter two categories, various things can happen. For example, if you're playing a wizard and you roll a partial success, you (the player) get to choose between the following complications:
  1. You draw unwelcome attention or put yourself in a spot. The GM will tell you how.
  2. The spell disturbs the fabric of reality as it is cast—take -1 ongoing to cast a spell until the next time you Prepare Spells.
  3. After it is cast, the spell is forgotten. You cannot cast the spell again until you prepare spells.
If you roll a failure (rather than a partial success), the GM gets to make a soft or hard move. This should follow from the fiction, but need not only affect your character. An example might be a wizard casting sleep and having it affect the rest of the party instead of the monsters.
 

Jediking

Explorer
DnD 3.5e includes a spell-casting check when a character is deafened (something I added to my 5e games). Not sure what exactly you want the consequences to do, but loss of a spell slot is the first thing that comes to mind.
Burning an Action (or turn, whatever you are playing) and a limited resource can be a huge deal depending on the game

Deafened
A deafened character cannot hear. She takes a –4 penalty on initiative checks, automatically fails Listen checks, and has a 20% chance of spell failure when casting spells with verbal components. Characters who remain deafened for a long time grow accustomed to these drawbacks and can overcome some of them.
 

Khelon Testudo

Cleric of Stronmaus
Hmm... a failure/blowback would logically happen on a roll of a 1 by the caster, or a 20 by the saving throw target. But to avoid too much, you'd limit it to the first attack roll or save, since spells may have multiple of either. The blowback could be 1d4 damage based on the damage type of the spell, or if the spell doesn't have a damage type, the spellcaster suffers the effect of one roll on the table for the Confusion spell until the end of their next turn.
 
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Ath-kethin

Elder Thing
The 2nd Edition AD&D psionics system was based originally on the proficiency system; each time a character used a power they had to make a check. Each power also included two variant effect: one for perfect success and one for catastrophic failure. We ran many games back in the day that used that system in place of the standard magic rules.

NOTE: a revision to 2e psionics switched the mechanical aspects of these powers from the proficiency system to the combat system, but the allowance for the critical success and failure didn't really change.

There is a 5e supplement on DMsGuild that emulates this psionic system for 5e; you can find it here: A Classic Psionic System for 5e - Dungeon Masters Guild | Dungeon Masters Guild. It's a little rules-heavy for 5e, but any system that incorporates critical success and failure for magic is pretty much going to be.
 

uzirath

Adventurer
IIRC, Rolemaster's magic system (in Spell Law) from way back included an extensive spell failure table for attack and non-attack spells. It included everything from mild failures to damage, unconsciousness, strokes, and even instant death. You might be able to dig it up with a bit of Googling.
 

pemerton

Legend
IIRC, Rolemaster's magic system (in Spell Law) from way back included an extensive spell failure table for attack and non-attack spells. It included everything from mild failures to damage, unconsciousness, strokes, and even instant death. You might be able to dig it up with a bit of Googling.
This is true.

Burning Wheel has spell failure rules that include the possibility of miscasting and also unwanted summoning (as happens to Ged in A Wizard of Earthsea).
 

the original Deadlands system used a card draw mechanic, where you had to get a certain poker value to succeed. Failure normally didn't have any consequences, but a few did IIRC. The worst part was if you drew a Joker, because while it was a wild for making your hand, just drawing it caused bad stuff to happen.
 

rustydm

First Post
Thanks for these responses. I can see now why players & GMs probably never bother with magic failure rules. The mechanical systems all seem fiddly. Dungeon World's narrative approach looks like the best way to fold it into the general gameplay without being a nuisance.
 

Lanefan

Victoria Rules
Thanks for these responses. I can see now why players & GMs probably never bother with magic failure rules. The mechanical systems all seem fiddly. Dungeon World's narrative approach looks like the best way to fold it into the general gameplay without being a nuisance.
The simplest 'failure system' is to just make spellcasting take time in the game (rather than instantly happen on that character's initiative) and during that casting time make it VERY easy to interrupt. Casting in melee is impossible*. Casting when restrained in any way is impossible*. Casting while taking ongoing damage is impossible*. 'Combat casting' options, feats, etc. do not exist. Etc.

Then, when a spell is interrupted, one die roll to see if a wild magic surge is generated and if necessary another to see what happens. Hardly what I'd call fiddly. :)

* - unless the caster's intent is just to try and trigger a surge (I've seen this done!), in which case start with the does-a-surge-happen roll.
 

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