Whenever Thrummingbird deals combat damage to a player, proliferate. (You choose any number of permanents and/or players with counters on them, then give each another counter of a kind already there.)
Illus. Efrem Palacios
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KHANS OF TARKIR 
COMMANDER 2014
FTV: ANNIHILATION 
SPEED vs CUNNING 
MAGIC 2015 
CONSPIRACY 
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