Assault Ops/Halo: Spartan Strike
From Halopedia, the Halo wiki
Halo: Spartan Strike also features three mission-specific Assault Ops for each of its 30 levels, making for a grand total of 90 Assault Ops.
Operation A: Orphic Spear
Operation B: Steadfast Pursuit
Operation C: Valiant Hammer
Operation D: Adamantine Shield
Operation E: Brother's Keeper