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 Foil - £1.00
Lightly Played Foil - £0.90
Moderately Played Foil - £0.70
Heavily Played Foil - £0.50
Damaged Foil - £0.30
Near Mint Foil Non English - £1.00
Lightly Played Foil Non English - £0.90
Moderately Played Foil Non English - £0.70
Heavily Played Foil Non English - £0.50
Damaged Foil Non English - £0.30