Mikaeus, the Unhallowed + Thunderblust + Yahenni, Undying Partisan

Mikaeus, the Unhallowed

Thunderblust

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Thunderblust.
2. When Thunderblust dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Yahenni ability.
4. Activate Yahenni by sacrificing Thunderblust.
5. When Thunderblust dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Yahenni ability.
7. Repeat.