In a campaign I'm running now, I'm trying to populate a dungeon with some nasty critters that were bred/engineered to be perfect killing machines. Initially, I used Unfettered Eidolons rebranded as aberrations, but now I'm having second thoughts. I don't have a lot of skill crafting eidolons, and while it was an effective challenge the first time, I'm worried if may get a little dull for the party to keep running up against the same one that's listed in the Bestiary.
Anyone who's familiar with Book of Vile Darkness or can get their hands on a copy, there was a truly nasty aberration in there called a Kython, with multiple challenge ratings and variable abilities. I'm curious how the two stack up next to one another in terms of lethality and variability as foes. Anyone have any opinions or advice on which to use?