Ouro Kronii

Hexproof, indestructible
At the beginning of each upkeep, if you're above
your starting life total lose 1 life, if you're below
your starting life total gain 1 life.
Pay 12 life, {t}: Take an extra turn after this one.
Activate only as a sorcery, and only if your life
total is exactly your starting life total.
"How many times are we going to do this?"