Invulnerability



The invulnerability is a powerup that makes the player generally impervious to damage. The player is not protected from telefrags, and will still recoil from a successful attack. The powerup looks like a green sphere with a grinning red-eyed head inside. While it is active, the colors in the player's view change to inverse monochrome, and the eyes of the status bar face glow yellow (STFGOD0), making them look similar to the demon's. The inverted monochrome display makes the game effectively fully bright, and the player will be able to see every detail even in the darkest areas. Spectres in particular become much more visible under its effects.

Invulnerability lasts for 30 seconds; in the last few seconds the display will begin blinking back to its original colors. Picking up an invulnerability before a previous one has expired resets the duration to 30 seconds.

Invulnerability can also be activated with the cheat code.

In deathmatch mode of vanilla Doom, invulnerabilities and blur artifacts never respawn. Some source ports allow flags to be set to cause them to respawn.

Invulnerabilities are included in the items percentage displayed at the end of each level.

Technical
According to the function P_DamageMobj in, invulnerability only protects the player from attacks doing less than 1000 points of damage; while no monster in the game can do nearly that much damage in one attack, a telefrag inflicts 10000 points (and indeed will kill even an otherwise invulnerable player). This also means that DeHackEd can be used to circumvent the invulnerability powerup by creating incredibly powerful weapons.

Appearance statistics
In classic Doom, invulnerabilities are first encountered on these levels:

The IWADs contain the following numbers of invulnerability artifacts: