Contagion Engine 145 (Scars of Mirrodin)

When this artifact enters, put a -1/-1 counter on each creature target player controls. {4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

NM - $24.20
LP - $19.30
MP - $14.50
HP - $9.70
DMG - $4.90