Tuesday, August 24, 2010

"Are you sure this is a good idea?" Casting spells from damaged spellbooks

Zak's post over at Playing D&D with Porn Stars discusses "poorly remembered spells": giving a wizard an extra spell of any level that has a 50% chance of backfire.  It reminded me of my own set of rules for memorizing spells from damaged (or poorly understood) spellbooks.

In my 3e Freeport campaign, the players were shanghaied aboard a slaver ship bound for the Caliphates, which took an unexpected turn in bad weather and wrecked on the shores of an island near and dear to any old-schooler's heart - the Isle of Dread.  The wizard was stranded without his spellbook, but soon discovered the book of another mage - ancient, weathered and heavily damaged, with some spells legible and others…not quite as complete.

"This time, for sure!" — B. Moose
For each of the incomplete spells, I prepared a short list of spells related in some way to the original spell - maybe a thematic or elemental relationship, with some spell effects lower than the level of the spell and some higher.  Whenever the spell was cast, a die would be rolled to find out how the magic actually manifested.  A successful roll on an appropriate skill or attribute (Spellcraft in 3e) will allow you to realize what form your magic is going to take in time to change targets (if necessary).

As an example, a partial fireball spell might look like this:

  1. lesser fire orb
  2. flaming sphere
  3. flame bolt
  4. fireball
  5. wall of fire
  6. resilient sphere (they were out of fire, so you just get the ball)

While invisibility might be a bit different:

  1. disguise self
  2. invisibility
  3. glitterdust
  4. darkness
  5. displacement
  6. improved invisibility

For added complexity, you could roll a Fudge die (if you don't have one handy, use 1-2 for a -, 3-4 for a blank, and 5-6 for a +) and give a further bonus or penalty based on that result.  3rd edition makes it easy - just choose a random metamagic feat to apply on a plus, and do the same but reverse it for a minus.  For earlier editions, roll 1d4:

  1. A random aspect of the spell (range, duration, casting time, # of targets, etc) is doubled/halved.
  2. Caster is treated as being 1d4 levels higher/lower for purposes of the spell.
  3. Target gets a +2 bonus/penalty to save, if any.
  4. Other change (damage/element type, reversed spell, etc)

Since the results are random, tilt the tables slightly towards a net positive - especially if your player is being forced into using spells like this (like mine was).  Even if they're using them by choice, they're giving up control and the ability to plan tactically for their effects.  For the same reason, put some care into picking the effects - don't go for opposites (faerie fire for invisibility, for example) but for interesting twists that can be used in similar ways (glitterdust can blind an opponent as well as reveal an invisible creature)


  1. I remember really enjoying these rules.

    I tried to use a summon monster spell and accidentally fired a dire weasel at a cannibal (bolt of conjuring I think). I also remember getting a large flaming sphere rather than a normal one.

  2. I presume there's no need to limit the possible tries to spells of the mage's usable level?

    I think my issue with this would be somewhat akin to virtually any untrained person using a chainsaw or a flamethrower without A)any instruction or B) possibly without having even seen the effect desired. In other words, 95-99% failure rate, with a very good chance of the spell and magic getting vastly out of control ... ie., causing more damage than usually expected, but in every direction.

    I haven't read Zak's post yet. Going there now.

  3. Generally I tried to center the effect around the spells actual level, and only go a level above it (maybe two, depending on the spell). You'll notice I didn't include delayed blast fireball in the possibilities…

    As for untrained - I would never let a non-wizard do this at all, and I assume that wizards in any edition are trained experts in the use of magic, so they can make educated guesses as to how to fill the details in - hence the fact that the spell actually works instead of fizzling! You might choose to represent that with some sort of skill or attribute roll, the results of which might even be able to affect the results on the table.