The Commoner's Revenge is a long range artillery unit.
Offensive: Effective all around artillery. It is fairly cheap to deploy and though the fire rate may seem slow there is no deploy time for it so it gets a lot of shot off before going down. Damage and range are very high though like most artillery it requires an armored escort to be effective.
Defensive: By itself it can still get a shot off and if left alone can cause Serious damage against the opposition so get those helicopters out their fast. Fast and long range tanks works as well just be sure they have a lot of health. Probably best to counter them with equally long range artillery just be prepared to trade unit for unit unless you also provide fodder.
The Commoner's Revenge is the cheapest variant but also has much higher stats due to it being Ultra Rare. With the recent buffing of the UR's this can demolish it's SR variants.