Rune of DOOM

Rune of DOOM is a quest item received during the quest A Show of Force.

Trivia
The Rune of DOOM has been confirmed as a reference to the classic First Person Shooter computer game DOOM.

The variations Doom and DOOM have both been used in official contexts. The variation DooM, stylized after the game's logo, is also occasionally encountered, but has fallen out of use almost completely in recent years. According to John Romero, the correct variation from the very beginning was DOOM and all others are incorrect. It remains unclear which variation is supported as "official" by id Software.

For more information please refer to the Wikipedia article on DOOM.