Skills related to the ammunition cart can be created (machine handling -> poisonous projectiles -> enchanted projectiles):
The following skills work if the hero has an ammunition cart. If it is destroyed, all abilities disappear.
Poisonous projectiles - which endows all ranged units in the hero's army with the "Poison" ability. The poison damage depends on the level of the "Machine Handling" skill and the hero's level: number of creatures in the army * 0.5 * 0.15 * hero's level. The chance of poisoning depends on the level of the machine handling skill (basic - 20%, advanced - 30%, expert - 50%).
Enchanted projectiles - a skill that allows your ranged units to cast dark magic spells in ranged combat, if you have:
Basic machine handling - slow; chance - 30%
Advanced machine handling - weaken; chance - 40%
Expert machine handling - destructive ray; chance - 50%