Treacherous Puppetry

Enchanted Creature has Indestructible,
Hexproof and attacks each turn if able
This creature gets +6/+6
At the beginning of each player's upkeep, that
player gains control of enchanted creature
At the beginning of each upkeep, put a -1/-1
counter on this creature
First comes darkness, then comes pain. Soon
enough, you'll be insane!
—Spirit of the Night