On every kill, three wasps chase the nearest opponent for 5 seconds. Each one deals half a heart and dies stinging.
Killing gives you nothing directly: no healing like the Vampire, no tail like the Kitsune. What you gain is time — three wasps going after the next player while you catch your breath.
On a server where fights come one after another, stopping the next opponent from refilling in peace is often worth more than two hearts.
A heart and a half in total if all three connect: that is pressure, not an execution.