Invincibility

Invincibility is a new piece of equipment featured only in Halo 3.

It confers the user with a brief period of invulnerability. This period lasts about 10 seconds. When activated the player is covered in shining white bands. It is known to be possessed by most Brute Chieftains that wield a Gravity Hammer unhindered, giving them a significant tactical advantage, as you cannot harm them. In campaign, it can be found on some dead Brute Chieftains that haven't used the power-up, but this is a rare occurence as they will usually activate it the second they are attacked. Curiously, if you melee a Brute in the back (assassination hit) while the invincibility is active, it will still kill him as if it wasn't active. In addition to being obtainable from dead Brute Chieftains, there is an Invincibility in the level "Halo". At the top of the Control Room tower, where you have to fight hordes of Flood, there is an Invincibility. After going up the staircase, go to the left and into the tunnel. It will be there. Note: This is only found on difficulties Easy, Normal and Heroic. It cannot be found there on Legendary.

It has a similar appearance to the Cloaking equipment, except that it glows a gold color, rather than a cool blue color. It's symbol on the HUD is Two overlapping, intersecting ovals.

It is not present in Multiplayer, unless you edit gameplay options where you can make players invincible. Note: The Guardians can still kill you.

In campaign, though you will be invulnerable from almost all forms of attack, you may still die from falling or having a large object such as a Scorpion crush you, or by having tons of Infection forms infect you. Invulnerable characters like the Arbiter who become betrayed by you after you kill them can also kill you easily.

Trivia

 * A player is able to take a Brute Chieftain's Invincibility if they assassinate, head shot, or in some way kill the Chieftain before he has a chance to activate and use it.
 * Despite being invincible, a player can assassinate a Brute Chieftain or another player successfully.
 * The Invincibility has an analogous effect to Tartarus's shields.
 * most useful when used for running at large groups of enemies head on blowing them to pieces as you go as they are unable to harm you without assasination somthing that is imposible if you're running right at them

Disadvantages

 * Players or AI who have activated the Invincible power-up can still be killed by being assassinated, crushed by large objects, or falling from a large height.
 * It only lasts for a short period of time(around 10 seconds), so it should only be used as a last resort, not the first chance you get.
 * As the equipment glows a gold/white colour, it can make you more visible when used and so might attract unwanted attention towards you.