Eccentric Apprentice

To venture into the dungeon, a player moves their venture marker into the next room of the dungeon they are currently in. If they aren't currently in a dungeon, that player instead chooses a dungeon card from outside the game, puts it into the command zone, and moves their venture marker onto the first room.

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.

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.

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.

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

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

Eccentric Apprentice's last ability works even if it wasn't on the battlefield when you completed a dungeon and even if the dungeon was completed on a previous turn.

A creature that becomes a Bird this way loses all other creature types but does not lose any of its abilities.

The last ability will overwrite any previous effects that set the creature's power and toughness to specific numbers. Effects that otherwise modify the target creature's power and toughness will still apply no matter when they took effect. The same is true for +1/+1 counters.