Tick

"Well, that's not coming off"
Entity ID	5.350.53

The Tick is a trinket.

Effects

• Removes 15% of any enemy's health if they have over 60 HP.
• Gives Isaac one Red Heart if he enters an uncleared Boss Room.
• Once picked up, it can't be removed.
  • The Tick can be replaced by Match Stick.
    • The Tick cannot be replaced with the Match Stick if Isaac has Mom's Purse or Belly Button.
  • The Tick can be removed by absorption by Marbles, Smelter, and Gulp!.
  • The golden version can be removed.

Notes

• This trinket can be used to infinitely replenish health if Isaac has access to any infinitely usable teleportation effect (such as Broken Remote + How to Jump).
• Only works on the first stage of multistage bosses.
• This trinket's effect can be multiplied to a maximum of x2 through any combination of multiple copies, golden variants, and Mom's Box.

Trivia

• Being able to replace the Tick with Match Stick is a reference to how one can remove a tick that has latched onto their skin in real life with a heated tip of a match stick; however, removing a tick like this can expose oneself to disease-causing bacteria present in the tick. It is also a feature that was carried over from the original The Binding of Isaac, though it's unclear why it wasn't originally added in Rebirth.
• The Tick is the only trinket that passively changes Isaac's appearance.
• The Tick bears similarity to a real-life deer tick.
• This trinket is used in The Host (challenge #18).