Jekyll, Thievery Savant

Flash
When Jekyll, Thievery Savant enters the battlefield
gain control of gain control of target permanent
until Jekyll, Thievery Savant dies or is exiled.
Whenever you gain control of a permanent
create a treasure token.
Sacrifice 5 treasures: gain control of target creature or artifact
an opponent controls. Activate only as a sorcery, and only once per turn.
At the beginning of your upkeep if you control 7 or more premanents you don't own, you win the game.