Vault of the Deep

When you draw Vault of the Deep, put it onto
the battlefield entrapped under your control.
(Put it onto the battlefield face down as a 0/1 Mine artifact creature with defender and "When this
creature would die, instead turn it face up and exile it.
If it is a nonland card, cast it without paying its mana
cost." Players may not look at the card while it is face
down.)
{t}: Add {u} to your mana pool.