Rootwater Matriarch

A theft engine with a leash made of someone else's cards. The control grab is conditional on the target staying enchanted, which means the Matriarch does not steal a creature so much as it weaponizes Auras: hang an enchantment on an opposing body, tap, and it answers to you for exactly as long as it stays enchanted. Strip every Aura off it (or let the creature die and return Aura-less) and control snaps back. That dependency is what keeps a four-mana 2/3 from being a repeatable Control Magic on a stick. The ability is free to fire every turn, but each theft demands a separate enchantment investment, so the Matriarch is the spigot, not the whole machine. It reads like a quirky Merfolk body, but the engine it really wants is an Aura subtheme nobody quite built around it, leaving the card to live as a combo piece looking for its other half rather than a standalone threat. The Threaten-style steal effects of its era expired at end of turn; this one persists, but the price is a board-state hostage that any enchantment removal can free.