Skulltaker Halo 2: Iron

Skulltaker Halo 2: Iron is an achievement in Halo: The Master Chief Collection. It is awarded for collecting the Iron skull in Halo 2: Anniversary on High Charity while playing on Legendary difficulty. The achievement is worth 5 Gamerscore, and the Xbox achievement art is a still of Tartarus from the Halo 2: Anniversary cutscene in The Heretic.

Location
When you enter the final (the second) large Gravity Lift (do not confuse with smaller ones throughout the level), look up. A Skull will pass through you extremely quickly so you must start holding X (or your equivalent action button) a bit before you actually pass it to grab hold of it.