Keys to the House

Two abilities on one artifact that barely acknowledge each other, and that split personality is the whole design. The first is a basic-land tutor bolted onto a sacrifice cost, the lineage that runs back through the various one-mana land-fetchers that smooth a draw while thinning the deck; nothing about it needs the door subgame to function, and it plays fine in a deck that owns zero Rooms. The second is bespoke: a sorcery-speed lever for locking or unlocking a door of a Room you control, which lets you revisit a choice Rooms otherwise settle once and leave alone. Because both modes demand the artifact be sacrificed to activate, each is strictly a one-shot; you pick which job the card does before it goes to the graveyard, and it never sticks around as an engine you leave on the table. The door-flipping mode explains why this exists at all, handing the Room subgame a switch to change a locked or unlocked half after the fact rather than only at entry. Stapling a generically useful fixer to a narrow, archetype-specific effect is the trick here: even in a deck with no door work to do, the tutor half still earns the slot, so a build-around tool gets to ride along in decks that only want the mana.