Whenever a creature an opponent controls dies, Altac Bloodseeker 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 Desperate Bloodseeker enters the battlefield, target player mills two cards. (They put the top two cards of their library into their graveyard.)

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 artifact: Draw a card.")

Sacrifice two Blood tokens: Transform Restless Bloodseeker. Activate only as a sorcery.