A tower which allows you to change the health of your OWN creeps, though with the loss of less money per kill, could be pretty useful if you are about to leak a creep...
Allows you to define if a tower should recieve either a: Attack speed buff, Attack damage or Range buff.[should only be able to target ONE tower if targeting more towers it would be OP]
A tower which you can patrol around an area(ex the first 2 corners) and it would do AOE damage to the creeps it walks over... Should be slower than all creeps and proberly max a amount of these towers to be made
My odd ideas