While holding this trinket, if there's another familiar that follows Isaac's Head, dropping this trinket will move the familiar to the first familiar slot.
This resets upon quitting and re-entering the game.
This is useful with familiars that are more effective when closer to Isaac, such as Lil Brimstone and Incubus.
Familiars that follow behind Isaac have a certain priority in how close their position is to him over other familiars, with Isaac's Head having 5th / 7th priority.
Synergies
Golden Trinket / Mom's Box: Tears deal Isaac's damage. Having both raises the damage to Isaac's damage x 1.5.
Sacrificial Altar: Sacrifices the familiar, destroying the trinket and generating an item normally.
The head shoots once per second.
The head shoots once every 3/4ths of a second.
Lil Brimstone and 
Incubus.
5th / 
7th priority.
Golden Trinket / 
Mom's Box: Tears deal Isaac's damage. Having both raises the damage to Isaac's damage x 1.5.
Sacrificial Altar: Sacrifices the familiar, destroying the trinket and generating an item normally.
Box of Friends: No effect; does not duplicate.
??? as Isaac.
