Guillain

Guillain is an NPC in Dead Cells who provides the player with a mutation between each two biomes, up to 3 Mutations at a time. After choosing mutations, the player can choose to reset his picks for a fee of 1000 gold the first time. On the second and third time, the price can increase up to 25 000 and 50 000 gold.

Not much is known about Guillain. He sits happily next to the pile of corpses left by the Beheaded in his previous attempts. his proximity to the Collector seems to imply he knows him or works with him. Guillain looks similar to the merchants, as well as the Blacksmith and his Apprentice. All of these characters have a chameleon/goblin-like appearance and seem to be of the same species.