Slasher is a bacon hair named Jason who was captured during the war in The Last Guest. He was sent to Area 51, the same from the famous ROBLOX game Survive and Kill the Killers in Area 51. Slasher would then be experimented on in the site, until he managed to get his hands on the Necrobloxicon, a book parodying the Necronomicon, the Book Of The Dead written by H. P. Lovecraft.

The Necromicon is a fictional Demonic book, containing of curses and spiritual writings said to make anyone reading it go crazy. Written with horrifying imagery of ways to make the dead come back to life. The Necrobloxicon is likely just the ROBLOX version of this.

Slasher heard a motherly voice coming from the Necrobloxicon. Believing it to be his mother he now uses it to guide his actions.

Slasher would then presumably escape Area 51 in an coordinated breakout with Jeff the Killer and Slenderman his prison friends and later partners in crime.