why is your DM spamming Blasphemies at your party? Sounds like he's running a video game BBEG and not a villain with any depth to it...
I totally missed the Hezrou when I was looking at the Demons/Devils in the SRD, good catch. I stand by my statement that it's not a game buster though. I mean if you're fighting a Hezrou, there is supposed to be 4 11th level party members vs 1 Hezrou. So you'll take 1 round of no actions, but you still defend yourself at full AC and saves etc. and the Hezrou uses his standard action to use his Blasphemy SLA... which leaves no room for anything other than moving or quickened actions (which base monster has none of) so what does he accomplish with Blasphemy? Nothing. If this Hezrou has buddies, then it's not a CR11 encounter and will justifiably be on the verge of untenable for 4 11th level PCs
Also if you're encountering NPC's that have Karma Beads boosting their Caster Level, it probably means that the DM is not using NPC wealth to create their characters, so it should probably be a higher CR encounter, and thus either garner you more XP or not be encountered until you're higher level.
And any DM that is putting level 15 PCs against monsters/npcs with Caster Levels 20+ is asking for TPK regardless of whether they use blasphemy against the party...
Blasphemy is really only unbalanced when used improperly by a DM and I don't think it needed the cushoning it received with Pathfinder
EDIT: How's it hangin Felix?