Beetle

Level Up (You may pay {x} at any time to level up
this creature, where {x} is its level plus 1. Also it
starts on level 1.) Level 1 - If a +1 +1 counter
would be put on Beetle, whenever a creature
enters the battlefield give it +0 +1 (This stacks.)
Level 2 - If a +1 +1 counter would be put on
Beetle, whenever a creature enters the battlefield
give it +0 +2 (This stacks.) Level 3 - If a +1 +1 counter would be put on Beetle, whenever a
creature enters the battlefield give it +0 +3 (This stacks.)