Daelkyr along with hordes and hordes of hands-for-feet and legs-for-arms kind of abberations. It's a big part of the Eberron backstory and there should be a lot more to do with them. Pretty much every abberation in the setting was made by the Daelkyr, including Illithids.

And just to top it off, a raid at the culmination of all this Dalekyr content could involve multiple Daelkyr! The off-tanking nightmare would be mind bending.