i doesnt have to be "spikes", i just havnt had a creative enough name to com up with. The most important thing is an abilty to cause damage with you shield over a period of time. The drain thing i mentioned seems to make the most sense and would be easist to implement.

the point is, is that tanks main objective is to take hits making it so they cant do damage so i would just like them to implement defensive skills that can do damage.