Clash

A clash refers to when two balloons essentially bash into each other, under normal circumstances, the winner is the biggest balloon, and the loser get's popped and sent to discard. but if both balloons are the same size then both pop at the same time.

Of course, card abilities can influence the outcome and aftermath of the class, such as effects that make balloons count as larger than their initial size during a clash, to effects that fire off when a balloon wins or loses a clash.