Tiari Gaal, Priest of the sun

Flying
At the beginning of your upkeep you may pay {x} mana and distribute {x} +1/+1 counters
among creatures you control,
they also gain flash until end of turn.
When Blocking, other creatures you control gain {x} +1/+1 counters where {x} is
Tiari Gaal, Priest of the sun's power & toughness