Mikaeus, the Unhallowed + Yahenni, Undying Partisan + Obstinate Gargoyle

Mikaeus, the Unhallowed

Yahenni, Undying Partisan

Obstinate Gargoyle

How it works

1. Activate Yahenni by sacrificing Obstinate Gargoyle.
2. When Obstinate Gargoyle 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 Obstinate Gargoyle.
5. When Obstinate Gargoyle 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.