The Brenner Head is always dropped by a Brenner after the player kills one. The player can pick up the head and use it as a melee weapon similarly to the Gridiron Ball. "Aiming down the sights" with the head will cause the player to use the head as a sort of flashlight, which emits a blacklight that can see invisible ink. Because of this, it plays a crucial role in activating the Voice of God within the Emperor's Chamber, which requires the player to obtain the four notes by shining the Brenner Head's blacklight on four paintings around the map.
In the hardcore version of the easter egg, the Brenner Head is also used to reveal the fingerprints on the two safes in the Laboratory and Morgue, which contains the two pieces used to unlock the seal in the Emperor's Chamber, which reveals the Red Talon.