Historical Rules · 23 July 2021
Rule 701.46a
Official source text from the 23 July 2021 Rules release
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.”