The Bombinomicon is a cosmetic item for all classes. It is a badge representing the twisted looking, leather-bound, haunted tome with glowing eyes named the Bombinomicon. A circle of jagged teeth clutch a bomb on the center of the cover.
Unlike many Halloween items, this cosmetic is not holiday restricted and can be used by players year-round. A player that dies wearing it will be gibbed in a spectacular explosion, with the color varying depending on the current day. During a full moon or Halloween, the explosion will be colored purple. Any other time during the year, the explosion will be colored gold.
This cosmetic is awarded to players who have earned the Dive Into a Good Book achievement by traveling to Loot Island through the portal that appears after MONOCULUS is defeated on Eyeaduct, then collecting the Bombinomicon held within a cage there. The Bombinomicon cosmetic can be awarded to multiple players who complete the listed specifications.
- The Bombinomicon was added to the game.
- [Undocumented] Updated the distortion effect on the Bombinomicon.
- [Undocumented] Updated the Bombinomicon effect to use golden particles outside of Halloween.
- The Bombinomicon no longer shakes the screen and has a delay before the explosion so that Snipers, Spies, and others can get better feedback on the actual cause of death
- [Undocumented] Updated materials for distortion effect of the Bombinomicon.
- The explosion effect still occurs when killed by a weapon that produces its own unique death effect: the Golden Wrench, Your Eternal Reward, Saxxy, Cow Mangler 5000, Righteous Bison, Short Circuit, Wanga Prick, Pomson 6000, Manmelter, Phlogistinator, Spy-cicle, Neon Annihilator, Golden Frying Pan, Batsaber, C.A.P.P.E.R, and Shooting Star.
- If the player uses the Feign Death from the Dead Ringer, the explosion will explode where the Spy is standing, rather than exploding on the fake corpse.
- If a player who does not have the Bombinomicon equipped is killed and leaves behind a ragdoll, then equips the Bombinomicon before respawning, the ragdoll will explode when the player respawns.
- The name "Bombinomicon" is a portmanteau of the words Bomb and Necronomicon, a fictional book from the works of H. P. Lovecraft.
- Despite being almost impossible to see it in-game, the model for the Bombinomicon has a back texture, which includes the back summary from the character Bombinomicon. Inside the book itself, it's also possible to find two pages with the Demoman class emblem, even though the book cannot be opened in any way.