I'm very (very) new to WM. I took the plunge when I was able to pick up a nearly-new 35-point eMagnus force for a knock-down price, and, having painted it (I know, I know; real WM players don't paint their armies, but I have a reputation to maintain) I've played a grand total of two 15 point games.
Obviously, I've got lots to learn. But one thing I feel like I ought to be able to grasp is the value of his Feat. The Feats of other casters seem really obvious as to how and when they are going to be useful. But his seems much more subtle and situational.
So what have I missed? How can I really mess up an opponent by using eMagnus's Feat?