03 January, 2011

Roll a d20 To Cast

The holiday season has left me mentally barren. I expect to recover soon.

In the meantime, I've been considering overhauling the basic underpinnings of magic use in my games, both wizard magic and cleric magic. My main intent is to have spellcasters rolling a d20 to cast a spell, just like players roll a d20 to make an attack. Since my main desire is some sort of equanimity, that means the higher the die roll, the better the spellcast.

Just like any system-fiddling, the first question is 'why bother, it works now.' Simple - I don't really like how it works now. I want my spellcasters doing magic. I'd rather it was more magic with less surety than less magic with more surety. I think that makes for a more interesting situation. Would it be any fun to play a fighter if you knew that you were guaranteed to do damage when you tried to hit.. but that you could only try to hit something once or twice a day? I'm thinking no.

I also have no interest in a wizard rolling 'to-hit' with their magic missile. Lame. I'm looking for something more interesting than that. I'm also thinking mostly about combat-related or time-sensitive magic. To be honest, if you can cast detect magic I don't really care how many times a day you cast it. Conversely, you probably don't care if it takes you 15 to 20 minutes to cast it. I think that's a pretty good trade-off, but I'd still like to see a d20 roll anyway, perhaps with a much easier target number, but with a chance to screw it up and make something bad happen, or even at least waste your time.

I love examples!

Charm Person: failure results in the intended target becoming insensibly enraged at the casting magic-user. They will immediately do their best to kill the magic-user, disregarding all other considerations to do so, including their own safety.

Detect Magic: failure results in a roll on the sensory mishap table.

Feather Fall: failure results in a roll on the minor physical mishap table, with all results visited upon the mage in the form of feathers and/or down.

One thing I really like about the take on this kind of system from James of A Dungeon Master's Tale is how (basically) target numbers get harder the more frequently you use magic. For what I'm after, the tables would look a lot more like one of Zak's tables, and the difficulty of successful spellcasting wouldn't increase quite as steeply as in James' system.

I'll keep thinking about this.. please throw ideas at me.


Greg Christopher said...

Check out the magic system in Errant for some inspiration.

HP fuels magic, but HP regenerates at a fast rate than classic D&D (because I made HP more like fatigue and take damage out of attributes).

I also have a much stronger emphasis on utility magics than the classic damage/combat oriented spells lists. For example, you can actually play an Abjurer or Enchanter and still be really bad-ass.

Free download too.

Sean Robson said...

Once again, we seem to be on the same wavelength regarding magic, Michael. I've been toying around with a skill-based magic system myself:

Roll 1d20 to beat a casting difficulty equal to 10 + spell level. The caster may add his appropriate attribute modifier to the roll. If the caster takes damage while casting the amount of damage inflicted is added to the casting difficulty.

A spell casting roll of difficulty minus ten or less results in a miscast, while a natural '20' results in the spell being automatically cast at caster level +1.

This system makes it difficult to cast high level spells, which is intentional as I'm trying to emulate a dark sword & sorcery feel; so using optional rare and hard-to-obtain spell components bestows a bonus to the casting roll, as does casting the spell as a ritual (10 minutes to cast), and sacrifice also bestows a bonus (+2 for animals, +5 for sentient humanoids, +10 for virgins).

I haven't tried play testing this yet, but the corruptive influence of magic is pervasive and most mages are unscrupulous and somewhat sinister. Mages that attempt to maintain a strict morality will always be at a disadvantage to those who will go to any lengths to obtain power.

Alexis said...

I must protest.

While I am deeply involved in the Same Universe Wiki, I must point out that the spellcasting page you link to and to which you refer was in fact posted by James from A Dungeon Masters' Tale. He deserves the credit for both the idea and for posting it on the Wiki. Please correct your blog post.

Alexis said...

I see where the error occurred. I was the last to edit the page, so it lists it as modified by me. I will bring that oversight to the attention of the IT master.

migellito said...

Thanks Alexis, corrected :)

migellito said...

Greg: I'll definitely check it out, thanks!

Sean: Once again indeed :) I like the basics you have laid out. I think for a base-line system, rather than using the sacrifices, etc., I would have the m-u add 1 to their roll per caster level. This would make a table pretty much the same as a fighter's to-hit table, with spell level standing in for armor class.

I really like the flavour given by the use of esoteric ingredients to get a casting bonus. Mechanically I see it as similar to the minor combat bonuses I give for ingenuity in fighting. Since this would only usually amount to a +1 or +2, I would probably use it in addition to what I said above, rather than instead of it.