"Tower" is a unique type of unit that can be used in a combat only by computer.
It can’t move.
A general feature of "Tower’s" life is health. It doesn’t have a moral parameter. It means that it attacks with an equal force till the moment of killing. "Towers" can’t be healed/poisoned that’s why the healers can’t be used against them.
"Tower" has two types of attacks: contact and distance attack.
Contact attack is pouring a pitch on enemy-units. "Tower" makes a back attack as a response to an enemy-unit contact attack.
Distance attack is made by two types of arrows: simple and freezing arrows. The list of a "Tower"s” arrows is shown over the "Tower". Order of freezing and simple arrows is random.