The Bat Bat is a MagicalMelee Weapon in Don't Starve. It deals 42.5 damage per hit and has 75 uses. Each hit leeches 6.8 from non-wall targets, but drains 3.4 from the player if they are not at full health.
The Bat Bat's leeching ability makes it ideal for fighting dangerous enemies that cannot be easily outrun, like numerous Hounds or giants (especially Dragonfly), while wearing armor; there may be no opportunity to stop and use a healing item, but striking provides the much-needed quick healing.
The Bat Bat is immensely useful for Wormwood, since it allows him to easily regain the health he cannot receive from healing foods. He is also able to easily obtain the living logs needed.
Batilisk Wings needed for Bat Bats can be farmed by setting up Rabbit Hutches near an open Sinkhole. The Bunnymen will come out at night and quickly kill any spawning Batilisks. This will also generate Guano and Monster meat as a byproduct.
A quick way to regain health is to attack Chester, Packim Baggims, Ro Bin, or Hutch with a Bat Bat, since their health regenerates quickly.
Maxwell's Sanity boost will make up for the Sanity lost from each hit when using this weapon. The health bonus is also welcome, since he has low max health.
This weapon will heal a total of 510 HP while draining 255 Sanity in its lifetime. This is equal to 17 Honey Poultices, 25.5 Healing salves, or 12.75 Pierogi or Fishsticks. In the absence of Jellybeans, the Bat Bat offers potent healing unaffected by spoilage.
Because of its low damage output, frail durability and healing utility, it is inadvisable to use this item as any other weapon. Rather, it is better off as a "sidearm" that one can swap to after losing health. Furthermore, it will drain sanity even if the user's health is full.
Bat Bats spawned in the ruins can provide helpful healing, especially if the player is underprepared or has intentionally come early.
Despite Wanda's quote for the Bat Bat, fighting with it does not restore Age.