I love endless mode type games, Horde/Firefight type stuff!
It'd be sick to see some sort of build up where you introduce the different abilities 1 at a time! Really just pointing that out because I really liked all the abilities in general (I didn't figure out the bone did tho). Grouping them all up and using the "E"! ability was my favorite to just lay out a bunch at once! Hah! Very neat!