Contagion Engine is a rare Artifact card from The List (PLST), collector number SOM-145. Current market price: $14.10, TCGplayer market prices via Scryfall.
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.)