Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight | Viscera Seer

Cards

All permanents on the battlefield (
Eirdu as Isilu, Carrier of Twilight and
Nearheath Stalker without a +1/+1 counter on it).

Activate
Viscera Seer by sacrificing
Nearheath Stalker.
When
Nearheath Stalker dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Resolve the
Viscera Seer ability.
Activate
Viscera Seer by sacrificing
Nearheath Stalker.
When
Nearheath Stalker dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Nearheath Stalker enters and dies as a state-based action due to having 0 toughness. Its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Resolve the
Viscera Seer ability from step 4.
Repeat from step 4.

If
Nearheath Stalker starts with a +1/+1 counter on it, then you may start the combo from step 4 instead.

This combo has been estimated to be Exhibition (Bracket 1+).