Skitter, Undersider

On your upkeep, create a 0/0 Swarm token creature
with 2 +1/+1 counters on it.

Whenever a Swarm you control dies, create X 1/1
Insect token creatures, where X is the number of
+1/+1 counters on it.

{b}, Sacrifice a Swarm: Regenerate Skitter,
Undersider