Traumatic Revelation is a common Sorcery card from March of the Machine (MOM), collector number 127. Current market price: $0.22 (foil $0.05), TCGplayer market prices via Scryfall.
Target opponent reveals their hand. You may choose a creature or battle card from it. If you do, that player discards that card. If you don't, incubate 3. (Create an Incubator token with three +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)