Solemnity + Phyrexian Altar

Solemnity

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing the persist or undying creature, adding one mana of any color.
2. When the creature dies, its persist or undying ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter or a +1/+1 counter on it due to Solemnity.
3. Resolve the Phyrexian Altar ability.
4. Repeat.