While I'm a little wary of Defensive Blast, my biggest concern is really it's fireball-ness, and lack of real consequences for the sorcerer.
While I haven't settled on anything definite yet, here are a few things I'm thinking about implementing.
- Defensive Blasts are not fireballs.
- Each sorcer has his own, unique defensive blast.
- DBs are dark and cthonic effects, calling on Primordial Forces That Should Not Be.
- Using DBs can inflict Con or other ability damage, Corruption Points, Insanity and/or other effects on the sorcerers using them. I may allow saves to reduce these effects.
- Someone effected by a DB should be left with psychological scars, even if the physical damage is minimal or short-term.
- Demons and Corrupt individuals may be slightly resistant to DBs.
Examples of possible DB styles include writhing tentacles, howling black winds, noxious vapours, spectres, alien psychic emanations etc... In any event, they should conjure the ideas of Wrongness and Doom intrinsic to Lovecraftian horror. Sorcerers should be loath to use them except in a true situation of last resort, and all but the most corrupt should probably hesitate even then.