Pete, Caller of the Crows

{b}{t}- create black 1/1 bird token creature
Whenever a bird dies put one dark counter on
Pete, Caller of the Crows.
At the beginning of your upkeep, there is 13 or
more dark counters on Pete, Caller of the Crows,
he gain the ability "Whenever Pete, Caller of the
Crows attacks create 2 black bird tokens attacking
and tapped"