From Halopedia, the Halo wiki
Post-Covenant War conflicts
The Annihilator missile is a type of plasma missile used as ammunition by the Blisterback mobile missile battery/heavy air unit.
Concept art of Atriox holding an Annihilator missile in Know Your Enemy.
Atriox feeling an Annihilator missile in Know Your Enemy.
A Blisterback firing its Annihilator payload.