+Bloodseeker (4)
Whenever a creature an opponent controls dies, this creature gets +2/+0 and gains first strike and haste until end of turn. (It deals combat damage before creatures without first strike, and it can attack and as soon as it comes under your control.)
Lifelink
When this creature enters, target player mills two cards. (They put the top two cards of their library into their graveyard.)
Discard a card: This creature gets +2/-2 until end of turn.
At the beginning of your end step, if you gained life this turn, create a Blood token. (It's an artifact with ", , Discard a card, Sacrifice this token: Draw a card.")
Sacrifice two Blood tokens: Transform this creature. Activate only as a sorcery.
Gatherer works better in the Companion app!
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, Discard a card, Sacrifice this token: Draw a card.")