MTG Keyword Rules — Comprehensive Rules Glossary

If a player is instructed to venture into the dungeon while they don’t own a dungeon card in the command zone, they 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. See rule 309, “Dungeons.”

If a player is instructed to venture into the dungeon while their venture marker is in any room except a dungeon card’s bottommost room, they choose an adjacent room, following the direction of an arrow pointing away from their current room. If there are multiple arrows pointing away from the room the player’s venture marker is in, they choose one of them to follow. They move their venture marker to that adjacent room.

If a player is instructed to venture into the dungeon while their venture marker is in the bottommost room of a dungeon card, they remove that dungeon card from the game. Doing so causes the player to complete that dungeon (see rule 309.7). They then choose an appropriate dungeon card they own from outside the game, put it into the command zone, and put their venture marker on the topmost room of that dungeon.

Venture into [quality] is a variant of venture into the dungeon. If a player is instructed to “venture into [quality]” while they don’t own a dungeon card in the command zone, they choose a dungeon card they own from outside the game with the indicated quality and put it into the command zone. They put their venture marker on the topmost room of that dungeon. If they already own a dungeon card in the command zone, they follow the normal procedure for venturing into the dungeon outlined in 701.49b–c.