Quash (previously known as Breach and often pronounced as "quāsh") is an artifact that can be played after a deal is made to cancel the deal, causing all involved players to suffer the appropriate penalties for a failed deal.
The timing of the artifact differs slightly in CEO, mostly because of the mechanics of online play: instead of canceling a complete deal, it is played during the dealmaking process.
According to leading experts, the quash is the most overpowered card in the game, along with the Mobius Tubes.