For this challenge you must complete all missions in Operation C with the Hollow skull active.
With the Hollow Skull active the Spartan only has a shield. Play each level of Operation C slowly and carefully allowing your shields to recharge when necessary. Keep an eye out for any Regen Fields during your play thru. When your shields are low activate with (LB) for a full shield recovery. If you are willing to spend XP then purchase the Oversheild Ability (Grants temporary invulnerability and an instant shield charge) for 400XP and a Shield Booster (Increases the Spartan's shield recharge speed) for 500 XP. The above Abilities and Boosters should make completing this challenge simple.
Good luck challengers