Hm, I like the idea with the Terror test also.
How about this:
Defensive Blast deals non-lethal damage instead of fire damage to all creatures in a 10ft-radius, 1D6 per PP spent.
They can take a fortitude save as usual, but they must also make a Terror test with a DC equal to 10 + half the damage dealt, or they flee in terror as described.
If a character meets the sorceror ever again and is hit by his Defensive Blast again, he must not make a terror test again, but instead he must roll against corruption (same DC) or gains an minor insanity.
If the poor soul then meets the sorceror a third time, and loses the save again, he gains a major insanity.
How about this:
Defensive Blast deals non-lethal damage instead of fire damage to all creatures in a 10ft-radius, 1D6 per PP spent.
They can take a fortitude save as usual, but they must also make a Terror test with a DC equal to 10 + half the damage dealt, or they flee in terror as described.
If a character meets the sorceror ever again and is hit by his Defensive Blast again, he must not make a terror test again, but instead he must roll against corruption (same DC) or gains an minor insanity.
If the poor soul then meets the sorceror a third time, and loses the save again, he gains a major insanity.