The floor is a selective Howling Mine for you and any player you want (except the player this is attached to). Playing more Curses means the enchanted player will die faster, but also that you and your friends get more cards.
How i feel about competitive players and casual players in EDH: The competitive are german tourists, the casual are italian tourists, both in a italian beach. The italians asking themselves "why are the germans here?" make a legitimate question, the answer is because the beach is beautiful, no matter the country you came from. The italians wanting to ban the germans are dumb, because if the germans pay for their stay and follow the rules like everyone else, they have the right to be in the beach. Hovewer, if the germans started to ask themselves "why are the italians here?"... they would be dumb as hell.
The art is spot-on, I wonder if this may end up seeing play in Standard if Ux Control is a thing. At 5 mana it's a bit of a reach, but attaching this to the opponent could break the mirror in your favor, so it could serve as a nasty surprise coming in from the SB.