Sefris of the Hidden Ways

Dungeon cards are not part of a player's deck or sideboard. In both constructed and limited formats, players can use any dungeon card when they venture into the dungeon.

You can only move forward (well, downward) in a dungeon, never backwards or sideways.

If you somehow venture into the dungeon while a room's ability is on the stack, you will continue on in the dungeon. If you're already in the last room, complete that dungeon and start a new one.

Moving into a dungeon room will cause its room ability to trigger.

The player venturing into the dungeon chooses which dungeon they will venture into. They may choose a dungeon that they have already completed this game.

Dungeons are removed from the game as a state-based action.

Sefris of the Hidden Ways' first ability looks only at the type the card has in the graveyard, not the type it had in any other zone. For example, animated lands dying won't cause the ability to trigger. The opposite is also true. For example, if a creature that was cast as an Adventure is countered, it's a creature card in the graveyard and the first ability will trigger.

Once you resolve the last room ability of a dungeon, that dungeon is now completed and is removed from the game.

A player may only have one dungeon in the command zone at a time.