Vault of the Ancients

Indestructible, Maddening
When you discover the Vault of the Ancients, you
are given two choices. You may leave the Vault be
and refuse the temptation to open it or Succumb
to the maddening whispers and open it. If you
choose to leave the vault, lose 10 life and sacrifice
it. Ancients cost {8} more for the rest of the game.
If you open it, destroy all creatures. Then, each
player searches their library for an Ancient,
reveals it and puts it onto the battlefield tapped.