Well, unless you're dealing with a half-fiend critter with 21+ HD... i.e. something that would be a cakewalk - if it couldn't auto-kill you with Blasphemy.If you're ten levels below the caster, you were going to die anyway.
Lowering the creature's caster level might be the only weay, but are demons and devils etc immune to level drain effects?
Ah, right. I'd forgotten about that ridicuous bug in the half-fiend template. As written, it's a recipe for epic-CL spellcasting at CRs in the low teens, which is not a sane way to make a balanced encounter.Well, unless you're dealing with a half-fiend critter with 21+ HD... i.e. something that would be a cakewalk - if it couldn't auto-kill you with Blasphemy.
Sounds like a reasonable houserule.IMC, the half-fiend SLAs get the same caster level as the base creature's most powerful existing SLA. If there are none, I fudge it and make its CL the same as its CR. This house rule meshes with my blasphemy one to make half-fiends a lot less broken.