The Key to the Vault
50PlayableLegendary Artifact — Equipment
Outlaws of Thunder Junction
2HG Rating
50/100
Plays about the same in 2HG as it does in any other format.
No 2HG-specific rules fire on this card — it plays much the same here as anywhere else.
Ratings start at a neutral 50 and are adjusted by rules derived from 2HG's structure — shared 60 life, shared turns, two opponents. They'll be recalibrated against real play rates once teams start submitting decklists.
Oracle text
Whenever equipped creature deals combat damage to a player, look at that many cards from the top of your library. You may exile a nonland card from among them. Put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.
Equip 
Legality
Plays well beside it
Fits the same colour identity — good candidates for your teammate's deck.
Suggestions are characteristic-based for now. Once teams submit pairings, this becomes a real co-occurrence score: played in X% of teams whose partner deck runs The Key to the Vault.