Obliterate

This land enters tapped. T: Add U. Transmute 1UU (1UU, Discard this card: Search your library for a card with mana value 0, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

(2/B can be paid with any two mana or with B. This card's mana value is 6.) Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

Add BBB. Threshold — Add BBBBB instead if there are seven or more cards in your graveyard.

Search your library for a white card, a blue card, a black card, a red card, and a green card. Reveal those cards, put them into your hand, then shuffle.

Dark Depths enters with ten ice counters on it. 3: Remove an ice counter from Dark Depths. When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

First strike, deathtouch Whenever a creature an opponent controls dies, you may return target artifact card from your graveyard to your hand.

1, T: Exile target creature you control. 7, T: Exile target creature you don't control. When Helvault is put into a graveyard from the battlefield, return all cards exiled with it to the battlefield under their owners' control.

1UU: Target permanent becomes an artifact in addition to its other types. (This effect lasts indefinitely.) 3U: Gain control of target artifact. (This effect lasts indefinitely.)