Haltimulicrum

At the beginning of your upkeep, choose an opponent.
Until the end step of that player's turn, creatures that player controls lose all abilities
and have "Whenever this creature deals combat damage to a player, you lose the game."
"Up there, look! The Haltimulicrum! To this day, no one knows how or why it appeared.. but we all know what happens to those who attempt to throw a rock in its general vicinity."