Mission: The Storm
Effect: Enemies have unlimited grenades... and use them OFTEN.
Instructions:Get to the first large area with Ghosts and Wraiths (not the area with the Scarab). The skull is waiting on top of the water tower in the middle. Parking your Warthog on the side of the tower facing the buildings (and away from the cliff) should give you the height necessary. Otherwise, use friends or a grenade jump. NOTE: Make sure the purple Wraith appears in the far corner, but do not destroy it. The skull will disappear if you do.