Mikaeus, the Unhallowed + Luminous Broodmoth + Phyrexian Altar

Mikaeus, the Unhallowed

Luminous Broodmoth

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing the creature, adding one mana of any color.
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. Repeat.