Arc-knight Sliver-bane

+1: Create 2 0/1 Saproling creature tokens with {3}: Sacrifice this creature, exile target Black, Blue, or Sliver Creature.
-1: Sacrifice a Creature: Each opponent sacrifices a creature, then sacrifices a Sliver Creature and loses 2 life for each Sliver they control.
-7: You get an Emblem: Slivers cannot grant abilities to other Permanents and {r/w}{r/g}{g/w}, Pay X life: Counter target creature spell with CMC