Regenerator
From Halopedia, the Halo wiki
Overview
The Regenerator emits a green field of energy which restores a player's shield as well as an enemy's. There is, however, a small delay before beginning the recharge, which means the player is still vulnerable, and you are vulnerable to rocket fire and head shots from a sniper rifle. It also won't help if a lot of people are firing at you. It is the exact opposite of the Power drainer and when it is used in the same area it loses its effect.
- Regenerator.jpg
The Regenerator on Sandtrap.