for those of you who don't know what skulls are, go to highimpacthalo.org to find out.
I've found a few. i'm tryin to find GRUNT B-DAY PARTY on "THE ARBITOR" level, but I keep dieing.i've found SPUTNIK, ASSASINS, BLIND, and what they call ''COWBELL''. If you need help trying to find one, ask me.