Skulltaker Halo 2: Mythic

Skulltaker Halo 2:  is an achievement in Halo: The Master Chief Collection. It is awarded for collecting the Mythic skull in Halo 2 Anniversary on Sacred Icon while playing on Legendary difficulty. The achievement is worth 5 gamerpoints.

Location
There is a semi outdoor area which has the same type of area right next to it. There is an Enforcer in front of each one. Go past this area and down the piston and you'll be in a very dark and dank Flood infested area. There's a stack of six or seven boxes as you enter the room. Use them to jump up to the landing above. There are a handful of alcoves on your right hand side. The Skull is in the third alcove, floating above a dead human Flood.