Hail Mary
From Halopedia, the Halo wiki
Hail Mary is a multiplayer and Spartan Ops medal in Halo 4. It is awarded for getting a long-range kill with a grenade.
Plasma grenade sticks can award a Hail Mary medal from the grave, provided the player who threw the grenade respawns at a spawn point far enough from the target.[1] If the player respawns BEFORE the grenade goes off (using the instant respawn system in most non-objective games) the Hail Mary will be awarded as if they had never died.
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