Moritte of the Frost | Yahenni, Undying Partisan

(and one other card)

Persist Creature

All permanents on the battlefield (
Moritte of the Frost as a copy of the creature with persist.).

Activate
Yahenni by sacrificing
Moritte of the Frost.
When
Moritte of the Frost dies, it triggers its persist ability, returning itself to the battlefield as a copy of the creature with persist with two +1/+1 counters and one -1/-1 counter on it.
Remove one +1/+1 counter and one -1/-1 counter from
Moritte of the Frost as a state-based action.
Resolve the activated ability from step 1, giving Yahenna indestructible until end of turn.
Repeat.