I second this game. The magic system is very reminicent of S&S tales. Using it also requires that you also incorporate their HP system. Basically, HP represent stamina and are easy to recover, but when your HP are gone, you take CON damage, representing actual wounds and damage.
Based on the Akratic Wizardry version (which was stated upthread as being the same as Crypts & Things, but I haven't looked at C&T to confirm this), it's definitely an improvement by attaching a cost (in HP and CON damage, as well as potential WIS damage from black magic) to spellcasting, but it still treats magic as a completely-predictable technology. Spells still work every time, their effects are just as predictable as in stock D&D spellcasting, and even the damage taken due to casting is completely predictable aside from whether or not black magic causes WIS damage (but, if you do take WIS damage, the amount is predictable). There's no chance of accidentally pushing yourself too far because the damage is fixed based on the spell level and known in advance. It adds cost, but does not add risk.
Also, as a side point, I don't care for the white/grey/black division. IMO, all magic should be risky and at least somewhat unpredictable.
My first-pass thoughts on incorporating the elements that I think are missing and doing so in a (relatively) simple way:
- In all cases, the terms "Cleric" and "Magician" are considered to include their subclasses and any other class casting spells belonging to that class or any of its subclasses. (e.g., "Cleric" would include a Ranger casting Druid spells and "Magician" would include a Ranger casting Magician spells)
- A Magician's Intellect Modifier is derived from Intelligence by the same progression used to derive Willpower Modifier from Wisdom.
- Characters can have a number of "available spells" of each level equal to their maximum spells per day of that level plus their Intellect Modifier (Magicians) or Willpower Modifier (Clerics). The number of spells of a given level that can be cast per day remains limited as usual, but any "available" spell may be cast. Making a "known" spell "available" takes a week and costs 100gp per spell level. When a new spell is learned, it may be added to the character's list of available spells immediately at no additional cost if there is an available slot for it. (This is basically the "Spell Repertoire" rule from ACKS, but with a 90% cost reduction for swapping spells into the "available" list. (1,000gp per spell level to move a known spell into your repertoire? Seriously?!?))
- When casting a spell, roll a d20 + CA - (spell level * 2) + Intellect (Magician) or Willpower (Cleric) Modifier. This is your Spellcasting Roll.
- If you have taken damage while casting the spell, roll a Concentration Check as per p.100 of the Players' Manual. The Spellcasting Roll is modified by an additional -2 per successful Concentration Check and -5 per failed Concentration Check. Even if one or more Concentration Checks were failed, the spell will still be cast normally. The only effects of taking damage while casting are the penalties to the Casting Roll.
- You may increase your Spellcasting Roll by inflicting 1 point of Strength, Dexterity, or Constitution on yourself per +1 to the roll. This must be done before making the Spellcasting Roll. Any damage inflicted in this way is recovered at a rate of 1 point per day and may not be healed by any magical means short of a wish or direct divine intervention (i.e., not simply a Clerical healing spell).
- Casting a spell via a ritual on an auspicious date, sacrificing rare alchemical reagents, extended casting times, voluntarily taking corruption, etc. may all provide additional bonuses to the Spellcasting Roll at the GM's discretion (and generally in accordance with the guidelines on p.124-126 of the DCC rules).
- To abort casting a spell in the face of unfavorable modifiers, or simply to avoid making a no-longer-necessary Spellcasting Roll, you must make a successful Saving Throw, adjusted by your Willpower Modifier. This must be done before rolling the d20 for Spellcasting and it still counts as one of your allowed spells for the day even if it is successfully aborted.
- If the final Casting Roll is a natural or modified 1 or less, you suffer corruption (Magicians) or divine disfavor (Clerics) and you must make a final Concentration Check to determine whether the spell goes off properly or misfires and causes an unintended effect of the GM's choice. If the final Casting Roll is less than zero, it is applied as a penalty to this Concentration Check.
- If the final Casting Roll is a natural or modified 20 or higher, the caster may increase any numerical aspect of the spell by 25% plus an additional 25% for each 2 points above 20 (50% with a Casting Roll of 22, 75% at 24, etc.) or gain some other equivalent improvement in the spell's effect, subject to GM approval.
- Corruption: Roll to determine whether the character is corrupted in a manner related to the spell's effects (1-2) or rolls on DCC's Minor (3-5), Major (6-7), or Grave (8+) Corruption table. This roll is made using a d3 for level 1 spells or a d(spell level * 2) for higher-level spells.
- Divine Disfavor: As DCC Deity Disapproval (p.122-123).
(OK, that's a lot more words than I expected. But it's still very simple in my head...)
I'm a little unsure of the Corruption roll (it should tend to be worse for higher-level spells, but 8+ on a d12 seems a bit too likely for a Grave effect, regardless of the spell level) and whether the bonuses for getting over 20 on the Spellcasting Roll might stack up too quickly, but, otherwise, it feels good to me. Does anyone see any errors, problems, or loopholes that I've missed?