Bison is the most basic unit available. It costs a single gold piece, smashes the fortifications with a force of 2 horns (just 2 for short) and might die after an attack.

Ram functions as a reinforced bison. It costs the same but hits for twice as much damage to the defences. It might get destroyed in an attack, too.

Catapult is the strongest weapon in the game. It carries the punch of five bisons for the price of two. However, it can only be used once.

Bison pen is an enclosure for your bisons providing them with breeding grounds. A single pen will result in one newly born bison for every ten bisons surviving a successful attack. Subsequent pens contribute diminishing returns.

Thief steals some of the treasures in advance, as opposed to after the fort's defeat.

Dark Mage resurrects a portion of your freshly deceased bisons and rams immediately following the battle.