Possessed Centaur

Target player discards a card. Draw a card.

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

T: Add C. T: Add B or G. Activate only if you control a Swamp.

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.) When this creature enters, exile target green or white creature an opponent controls. When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Flying When this creature enters, target player loses 3 life. When this creature leaves the battlefield, that player gains 3 life.

Until end of turn, if target player would draw a card, instead that player skips that draw and you draw a card.

Draw four cards, then choose X cards in your hand and discard the rest.

First strike Threshold — As long as there are seven or more cards in your graveyard, this creature gets +1/+1, is black, and has "2B, T: Destroy target red creature."