The vault's ultimate prize wasn't exactly what Kellan had imagined.

Loot, the Key to Everything

Ward {1}
At the beginning of your upkeep, exile the top X cards of your library, where X is the number of card types among other nonland permanents you control. You may play those cards this turn.

The Big Score

Lands are disregarded when calculating the value of X. For example, if you control an artifact land but no other artifacts, artifact won't count toward the value of X.

The card types that could appear among your nonland permanents are artifact, battle, creature, enchantment, kindred, and planeswalker.

The value of X is determined as Loot's last ability resolves.

You pay all costs and follow all normal timing rules for cards played from exile with Loot's last ability. For example, if the exiled card is a land card, you may play it only during your main phase while the stack is empty.