Modified Invincibility
From Halopedia, the Halo wiki
The Modified Invincibility is a very powerful piece of Equipment used by Tartarus Chieftain of the Jiralhanae, on the Halo 2 level The Great Journey. It is thought to be generated from the Fist of Rukt, and when active the shielding emits a white fog like substance that protects the user from all weapons, exept direct shots from Beam Rifle. It usually takes 3 shots to lower the shield on easy, but 5 shots or more on Heroic or Legendary. The Modified Invincibility is also much different from other types of Covenant energy shielding, because it can recharge itself if brought down, therefore granting the user invulnerability once again. It is never available to the player for use.