Invoker is a very open hero to builds, plese note that for invoker you may need to change the order og how much exort or wex you get for mid invoker. This is what i find to be the best over all way to skill a mid invoker and what items you will need for ganks, note that you should also look and tell you team that you can sunstrike an enemy. One of the most destutive exort midvoker skill chains is "tornado-chaos 'meat ball'-def blast.