(Waterveil Catacomb isn't a spell.)

Waterveil Catacomb enters the battlefield tapped unless you pay 2 life.

Waterveil Catacomb is indestructible. (Destroy effects and lethal damage don't destroy it.)

When Waterveil Catacomb enters the battlefield, put a land you control on the bottom of its owner's library.

: Add  to your mana pool.