Death's Oasis + Deathrender + Dutiful Attendant + Carrion Feeder

Death's Oasis

Deathrender

Dutiful Attendant

Carrion Feeder

How it works

1. Activate Carrion Feeder by sacrificing Dutiful Attendant.
2. When Dutiful Attendant dies, it, Deathrender and Death's Oasis triggers.
3. Resolve the Dutiful Attendant trigger, returning a creature card with mana value four or greater from your graveyard to your hand.
4. Resolve the Deathrender trigger, putting the creature with mana value four or greater from your hand onto the battlefield, and attaching Deathrender to it.
5. Resolve the Death's Oasis trigger, causing you to mill two cards and return a creature card with mana value two or less from your graveyard to your hand.
6. Activate Carrion Feeder by sacrificing the creature with Deathrender attached.
7. When the creature dies, Deathrender and Death's Oasis triggers.
8. Resolve the Death's Oasis trigger, causing you to mill two cards and return Dutiful Attendant from your graveyard to your hand.
9. Resolve the Deathrender trigger, putting Dutiful Attendant from your hand onto the battlefield, and attaching Deathrender to it.
10. Resolve both Carrion Feeder abilities from steps 1 and 6, putting two +1/+1 counters on it.
11. Repeat.