Sky Swallower

The drawback is the entire point, and it is a doozy: an 8/8 flier that, on entry, hands your opponent control of everything else you control. Lands, other creatures, enchantments, artifacts, the works. Played straight, it is a concession with wings. The design exists to be subverted, and the obvious subversion is to have nothing else worth losing: cast it with an empty board, or sandbag it as a last play, and you are simply paying five mana for a fat evasive body. The sharper line treats the trigger as a weapon rather than a cost, targeting the opponent so they gain control of permanents you have already poisoned: enchantments that punish their controller, artifacts that hurt to control, anything whose control is a liability. It is a rare creature whose enters-the-battlefield clause is written to be aimed at the person across the table, turning a symmetrical-looking handoff into a one-sided gift of problems. That gap between the literal text (a gift to your opponent) and the intended play pattern (a gift you want them to be stuck with) is what gives the card its puzzle-box reputation: the work is all in building a board state where giving everything away is the strongest thing you can do.