Stalwart Successor + Restless Apparition + Yahenni, Undying Partisan

Stalwart Successor

Restless Apparition

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Restless Apparition
2. When Restless Apparition dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Restless Apparition enters, Stalwart Successor triggers, putting a +1/+1 counter on Restless Apparition
4. Resolve the Yahenni ability.
5. Repeat.