When Contagion Engine enters the battlefield, put a -1/-1 counter on each creature target player controls. {4}, {T}: Proliferate, then proliferate again. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)
Near Mint - $18.80
Lightly Played - $17.00
Played - $13.20
Heavily Played - $11.30
Damaged - $9.40
Near Mint Non-English - $18.80
Lightly Played Non-English - $17.00
Played Non-English - $13.20
Heavily Played Non-English - $11.30
Damaged Non-English - $9.40