Eleron, Dragonscale Combatant

Eleron, Dragonscale Combatant enters the battlefield with two +1/+1 counters on it.
Whenever Eleron attacks, bolster X, where X is the number of +1/+1 counters on Eleron.(Choose a creature with the least toughness among creatures you control and put X +1/+1 counters on it.)