Skull Effect:Enemy units will throw grenades at an alarming rate.
Campaign Scoring Multiplier: 1.5x
Skull Location:The Cacth Skull is located near the middle of the fourth level, The Storm.
The Skull is located in the area where you need to destroy the first Anti-Air Wraith Tank. When you enter this area, do not destroy either of the Wraith Tanks (The skull appears when the Tanks appear, and disappears when the Tanks are destroyed). The Skull is located on top of the circular building next to the Anti-Air Tank.
You can easily get on to the roof parking a Warthog against the building and then grenade jumping from on top of it. Or on 2 player co-op, get one person to stand on the Warthog and then the second can jump up onto the building off that persons head.
It is a good idea to destroy all of the Ghosts in the area and snipe the gunners out of the Wraiths before trying to jump up.