Mikaeus, the Unhallowed + Luminous Broodmoth + Altar of Dementia

Mikaeus, the Unhallowed

Luminous Broodmoth

Altar of Dementia

How it works

1. Activate Altar of Dementia by sacrificing the creature.
2. When the creature dies, its undying ability triggers if it didn't have a +1/+1 counter, and Luminous Broodmoth triggers if the creature didn't have flying.
3. Resolve the undying trigger, if applicable, returning the creature from your graveyard to the battlefield with a +1/+1 counter on it.
4. Resolve the Luminous Broodmoth trigger, if applicable, returning the creature from your graveyard to the battlefield with a flying counter on it if the creature is still in your graveyard.
5. Resolve the Altar of Dementia ability.
6. Repeat.