Invisible grenade throw
From Halopedia, the Halo wiki
This is a special trick on Halo 2 where a player can throw a grenade without their character physically doing so.
The process is simple. Grab a Sentinel Beam and shoot until it overheats. Then when it is cooling down, throw a Grenade. The grenade will seem to be coming out of you as you cannot see your hand throw it. This trick works with both Human M9 HE-DP grenades and Covenant plasma grenades.
