Tristana, Rapidfiring Recruit

Gunfire X - {r}{1} (Whenever this creature
attacks you may pay {1}{r}, if you do, this creature
deals X damage to target creature) X is equal to
the number of counters on Tristana
Whenever Tristana deals damage to a permanent
with her gunfire ability, put a +1/+1 counter on
her, then if you dealt 4 or more damage to that
permanent this way, return it to its owners hand