Jellobirb

Whenever Jellobirb enters the battlefield under
your control, choose another player. When that
player casts a spell, you may ask that player if you
can counter that spell. If they say yes, counter
that spell and they gain control of Jellobirb.
During your upkeep create a Jello token. (It's an artifact with "1, Tap, Sacrifice this artifact: You gain
1 life.")

The early birb gets the gummiworm!