Unstable Swarm

When Unstable Swarm enters the battlefield, sacrifice all insect creatures you control. Unstable Swarm gains {x} +1/+1 counters where {x} is the total strength of every creature sacrificed this way.
If Fierce Flock would be dealt damage, prevent that damage and remove 2 +1/+1 counters from it, then create a 1/1 black green insect creature token.