| Floors of
| Base Health||300|
|Unlocked By||Defeat Isaac Ten Times.|
|Items Dropped||Boss Pool|
Triachnid performs a variety of attacks throughout the Boss fight, all of which are as follows:
- Triachnid will lift its head, showering each leg in random spots in the room, leaving white creep in each spot.
- Triachnid will spawn a Trite.
- Triachnid will lift its head all the way up, raining down each foot one at a time at Isaac's location, ending with slamming its head on the ground, shooting tears in an asterisk pattern and leaving white creep.
- Triachnid is a reference to the spider-like creature in the game Tri-achnid.