Rule 309.5 · Dungeons
The venture into the dungeon keyword action allows players to move their venture marker down the rooms of a dungeon card.
Subrules
If a player ventures into the dungeon while they own a dungeon card in the command zone and their venture marker isn’t on that dungeon’s bottommost room, they move their venture marker from the room it is on to the next room, following the direction of an arrow pointing away from the room their venture marker is on. If there are multiple arrows pointing away from the room the player’s venture marker is on, they choose one of them to follow.
If a player ventures into the dungeon while they own a dungeon card in the command zone and their venture marker is on that dungeon card’s bottommost room, they remove that dungeon card from the game. They then choose a dungeon card they own from outside the game and put it into the command zone. They put their venture marker on the topmost room.