Helltime power
From DoomWiki.org
Helltime power is the first powerup gained for the Doom 3: Resurrection of Evil's Artifact. It is gained by killing the Helltime Hunter. Helltime is comparable to such abilities as Max Payne's "bullet time", albeit much more advanced. When activated, time slows to a crawl around the player who continues to move quickly. It is very helpful in battle, allowing the player to easily outmaneuver monsters, often killing them before they have a chance to strike - in addition, easily dodging their return fire if any, and easily achieving headshots. Combined with the berserker punch strength, it can be used to kill many monsters in a hurry.
It is also very helpful in traversing two puzzles — a room full of crusher walls, and a pathway blocked by fast-moving blades (both of them can be traversed without Helltime, but with difficulty).