Starting from wave 2 onwards in Campaign mode, Gnoll Catapults will start to spawn on the crushed grass near the eastern corners of the map. They will then proceed to bombard your soldiers by throwing rocks at them.
Gnoll Catapults deal high damage and can most of the time easily kill soldiers and heroes with ease. They have unlimited range, though they do not stay to kill all your soldiers like other ranged enemies. Instead, they only fire several volleys before leaving. Letting a Catapult leave is not considered a leak, and does not reduce lives, but also does not grant the Catapult's bounty. Gnoll Catapults spawn every wave in Heroic Challenge mode.
Gnoll Catapults also make an appearance in Valor's Rest, the Endless Challenge level, in which they act very similar. However, they cannot be targeted by any attack, including Thunderbolt. In addition, they have extra attacks, including a barrage of rocks, a spiked ball, and barrels containing gnolls.