'''Effect:''' Enemies always drop 2 plasma grenades, and it appears that all enemies will toss more grenades in general.
+
+
'''How to get to the skull:''' Right after you exit from the underground highway, you'll come to a large open-air circular room with a handful of Jackal snipers and some Elites. The quickest way to get safely to the skull is to get the next checkpoint by jumping into the Warthog and letting the marine drive you to the next area. Jump out of the jeep and backtrack to the large room, and clear the area. You will see a large semi-circlular beam going from one of the main platforms that goes from the ground up to the top of the two towers. Do a grenade jump at the bottom of this beam and walk all the way to the top. Jump over to the ledge of the left tower. Walk to the end of the ledge and you will find the Catch skull.