From Destinypedia, the Destiny wiki
As opposed to the Shock Grenades used by Fallen Dregs, Acolyte Grenades explode instantly upon impact with the ground and causes damage over time. This requires players to be wary of when they are thrown, since they won't have a chance to escape from damage once the grenades have landed, along with dealing noticeable contact damage. Acolytes tend to use them as a tactic to force enemies out into the open from their cover or if they're staying too far away to be attacked with Shredders.
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