From the handbook (Page 35):
Watch Towers are a first line of defense for Aramon’s armies in the early stages of the war. Manned by capable archers, they can keep small armies at bay and are quite capable in support of defensive garrisons.
They are useful in protecting strongholds against flying units. Some flying units are too fast for the strongholds to hit, especially if a player opponent is moving them about regularly. Flying units can also fly too close to a stronghold for it to target them, able to easily get past any wall defenses that keep ground units from doing this. So watchtowers are useful in dealing with this vulnerability.
Watch Towers do not have many hit points so they need to be protected by gate barracks or other units.
Cost: 2751 mana
Build time : 30 sec
Hp : 5200
Weapons : - 1st archer 225dmg 2,5 sec for reload
- 2nd archer 225 dmg 2.4 sec for reload
Damage multipliers (same for both archers)