Windy City Elemental (UW05b) [Unknown Event]

Flying Ascend MagicCon Chicago (If you attended MagicCon Chicago and control ten or more permanents, you get the windy city's blessing for the rest of the game.) Whenever Windy City Elemental attacks, if you have the windy city's blessing, put a +1/+1 counter on each creature you control with flying.