To enable the battle against The Mycologists, select the Mycologists Boss challenge when starting a new run. They replace The Angler as the boss of the Wetlands.

Phase 1

They will play a variety of cards. When a card is queued to be played in a slot that already has a card, the two cards will be merged.

Phase 2

They will cut up all of your cards and combine them into a single card which will be drawn to your hand. This card will cost 1 blood per card used to create it. Everything in phase 1 applies in phase 2 as well.