Historical Rules · 13 October 2023
Rule 309.5b
Official source text from the 13 October 2023 Rules release
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.