Hi blizzard,how are you?
It seem,s that fort and keep are not so usefull in game,because thay only can attack 1 unit and their Max health and damage are not Increased douring the game.
For example See,when we stand in defense phase, enemy have at least 6 minions,3 heroes and more thing like as summons and Mercenary;but our fort and keep can only damage 1 number of them.
When fort,keep stand in attack situation,it is so useless,when it stand in Defense situation,it will be destroyed in 6 or 7 second.
Our fort and keep should can damage two aditional enemy for 60% of main damage,and also they can slow enemy Mp and Ap by 20%.
Also fort and keep should be upgrated every 7 minutes of game until they be empower and usefull.
Thanks for you.