Well, Just killed Archavon. He dropped 2 Priest pants. The same pants. Only one priest. /sigh. Oh Well. Dropped Archavon.

HELL YEAH!

As it turns out, clumping does work best as long as you tank him close enough to the group that he doesn't jump. Turns out it functions like any other random charge: He doesn't do it if you are too close. So for future reference, stay close, keep your clump healed, and Archavon is cake.