Ashling, the Limitless + Ashnod's Altar + Graveshifter

Steps

1. Cast Graveshifter for its evoke cost by paying {4}.
2. When Graveshifter enters, its first ability and evoke abilities trigger.
3. Resolve the first trigger, optionally returning a card from your graveyard to your hand.
4. Holding priority, activate Ashnod's Altar by sacrificing Graveshifter, adding {C}{C}.
5. When Graveshifter dies, Ashling triggers, creating a token copy of Graveshifter with haste.
6. When the Graveshifter token enters, it triggers, returning Graveshifter from your graveyard to your hand.
7. Resolve the remaining Graveshifter ability from step 2, doing nothing.
8. Activate Ashnod's Altar by sacrificing the Graveshifter token, adding {C}{C}.
9. Repeat.