Dark Bum usually floats behind Isaac, but if any Red Heart exists inside the current room, he will leave Isaac to pick up them for himself.
For every 1.5 red hearts he has picked up, he will spawn one of these thing shown below:
- A Soul Heart. This is the most common thing he spawns.
- A hostile spider.
- A friendly blue spider.
- A Black Heart. This is the rarest drop.
Little C.H.A.D.: Allows to gather easily more Soul Hearts if Little C.H.A.D.'s hearts remain.
Dark Bum can convert any red heart into soul hearts, therefore he is especially useful when playing as ???, Azazel, Eve or any characters that lack enough heart containers. To ordinary characters it is still useful, since in many occasions there are a large number of spare red hearts spawned upon cleaning rooms. Dark Bum is comparatively useless to characters with many heart containers like Magdalene.
The Best Friends Forever item will increase the size of the Dark Bum, but his function remains entirely unchanged.
Mac: Z42Q 9AKT (First treasure room to the left.)
Vita: 1XP8 MGFZ (First treasure room.)
Xbox: SDRS ZQ1B (Thrid treasure room.)
PC: LFC1 CDP3 (First treasure room.)