Casting Spells

Last night I kicked off a mini-campaign that will employ a simplified, hacked, and house-ruled magic system. The action only saw one spell cast, but it was memorable. The caster completely botched it and suffered a nasty spell complication.

But the complication was the icing on the top. The real fun came with the uncertainty inherent in the magic system and casting mechanics, which revolve around a d20 roll-to-cast instead of relying on spell points or spell slots. The spell being cast wasn't written in the rules and so it had a real air of mystery and sorcery. I couldn't be happier with the system's first test.

A sorcerer who has suffered from numerous spell catastrophes (art by Russ Nicholson)

Spellcasting works like this:

• Spellcasters specialize in certain types of spells: schools, circles, domains, whatever. They are proficient in casting those spells. They can cast other spells, but not as well.

• During every full rest (a rest spent in a safe haven), a caster can memorize a number of spells equal to their level.

• When they wish to cast a spell, they roll a d20 and add their INT bonus (and caster level / 2 if it's from their favored school), trying to exceed 10 plus the level of the spell.

• If they succeed, they cast the spell and remember the steps to cast it again.
• If they fail, they still cast the spell, but forget how to cast it again.
• A natural 1 results in bad news: everything goes bottoms up. The casting fails miserably and the caster suffers a catastrophe.

• If the spell requires an attack or contested roll, use the result of the d20 roll as the attack roll.

That's pretty much it. I'm using the magnificently zany supplement Wonder & Wickedness as the source of my sorcery schools, spell catastrophes, and several spells. The casting system itself draws inspiration from Dungeon Crawl Classics and Index Card RPG, for those of you interested in my influences.

One tweak I may consider once the players become more familiar: a less binary set of results for the casting check, based on my d20 reaction table. Something like:

< 2 Catastrophe! The spell fails, it's lost from memory, and the caster suffers a magical mishap.

2 - 6 Casting fizzles ... the spell fails and it's lost from memory.

7 - Target Lost focus ... the spell actuates but it's lost from memory.

> Target Textbook casting. The spell actuates and the caster can recall the incantation to cast it again.

Natural 1s always count as a catastrophe result, regardless of modifiers.