Xantcha, Sleeper Agent

Whenever another permanent you control enters, each opponent mills a card.

Target player mills three cards. Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

As an additional cost to cast this spell, sacrifice a land. Search your library for a land card, put that card onto the battlefield, then shuffle.

Choose a card name. Exile the top six cards of your library, then reveal cards from the top of your library until you reveal a card with the chosen name. Put that card into your hand and exile all other cards revealed this way.

Return any number of permanent cards with different names from your graveyard to the battlefield.

This land enters tapped. T: Add C. Whenever this land or another land you control enters, if you control seven or more lands with different names, create a 2/2 black Zombie creature token.

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each B in the mana costs of permanents you control counts toward your devotion to black.)

Target player discards two cards at random.