Sliver Juggernaut

{3}{u}{b}: Monstrosity 4 (If this creature isn't monstrous, put 4 +1/+1 counters on it and it becomes monstrous.)
When Sliver Juggernaut becomes monstrous, sliver creatures you control get Annihilator 1. If this creature is destroyed as a result of battle, exile it instead.
The end of existence.