How to Get the IWHBYD Skull in Halo 3: 8 Steps (with Pictures)
How to Get the IWHBYD Skull in Halo 3: 8 Steps (with Pictures)
Skull Locations FAQ - IGN
In Halo 3, when Truth fires all the Halo rings, there is a destroyed one, that does not light. This would be the Halo ring you destroyed in the first game. :