J'beign, Tyrant of Affliction

When J'beign, Tyrant of Affliction enters the battlefield, you get {e} equal to the amount of {g} spent on {x}.
{b}{g}, Pay any amount of {e}, {t}: Creatures you
don't control get -X/-X until end of turn, where
X is equal to the amount of {e} spent to activate
this ability.