Fayren, the Adroit Rogue

When Fayren, the Adroit Rogue enters the battle field or attacks, you may pay {u}{b}{r}, if you do, you get {e}{e}.
{e}: Put a +1/+1 counter on Fayren, the Adroit Rogue.
{e}{e}{e}: Destroy target nonland permanent with mana value equal to or less than the number of energy counters you have
{e}{e}{e}{e}{e}{e}: Destroy all other nonland permanents.