His main purpose is to egg on the player to make a "Sacrifice", which is done by using Mama Tick in the Nest, as well as provide the player with the Bound for Hell Achievement. After the sacrifice is made, he will become bloody, get a deranged look, and begins praising the player for said sacrifice.at the nearby alter. This will stop the player from having to fight
When walking up to the altar he is found beside, the Priest will exclaim:
- "A new disciple!"
Upon talking to them for the first time, they will say:
- "Welcome to our humble chapel brother! Are you ready to make a sacrifice?"
Subsequent interactions with the Swamp Priest will result in them randomly saying one of the following lines:
- "Pray for your salvation... with a sacrifice."
- "Words are meaningless, only sacrifices are important..."
- "Mama protect this lost child..."
- "Prove your devotion!"
- "Sacrifice will save you..."
- "Are you really faithful?"
When using the Mushroom Boi! near the altar:
- "THE SACRIFICE!"
- "Your sacrifice has been accepted."
- "Mama has blessed you."
- "A miracle... It’s a miracle..."
- "We need more sacrifices!"
- "...more sacrifices..."
- 1.8: Introduced.