Sliver Destroyer

At the beginning of your upkeep, sacrifice a
Sliver, if you can't, sacrifice Sliver Destroyer.
Sliver Destroyers power and toughness are equal
to the number of Slivers you control.
Slivers you control get Annihilator 1 (Whenever
this creature attacks, defending player sacrifices a permanent.)
"When we turned to see what we had run from,
all that remained was ash... and teeth" - Elvish Scout