[thejeff]

I don't know about Paralyze. Petrify is the bane of SCs, since it either kills outright or paralyzes.

MR checks work the same way for different spells, but you do get +1 penetration for every 2 extra levels of magic you have, so a 4S mage would have a bonus using Paralyze(S2) but not with Soul Slay(S3). He'd also get more of them off, since fatigue will be reduced more by his higher levels.