Flying
Whenever Thrummingbird deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Near Mint - $0.60
Near Mint Non-English - $0.60
Lightly Played - $0.50
Lightly Played Non-English - $0.50
Played - $0.40
Played Non-English - $0.40
Heavily Played - $0.40
Heavily Played Non-English - $0.40
Damaged - $0.30
Damaged Non-English - $0.30