Here’s a piece of the official description:

Upon glimpsing his fearful visage, most keep their distance, fortunately unaware that his touch bears a sinister scourge. Those who stumble within his grasp fall victim to incurable maladies. In fact, Mordekaiser seems mystically attuned to sickness, as if it feeds and comprises part of his chilling essence. He now stalks the slums of Noxus, drawn to the plague-ridden and diseased. However, there is something in his clever tactics, something in his noble stance, something in the tone of his unearthly commands that has led many to believe that Mordekaiser is more than just a foot soldier. Some see the distinguishing characteristics of a general. While many have learned to accept the evidence of this unsettling possibility, a lingering question keeps them wary at the witching hour: If Mordekaiser is a general, what nightmarish legion lurks at his command?

I’m excited to try him, but it seems he’ll fill a role shared by many – support tank/DPS. While those toons are fun, I find them to be pretty situational with regard to team makeup. Blitzcrank, Nasus, Singed – they can all be immensely fun to play, but are often hard to fit into a team setup. Blitz and Singed also bring some utility to the table with slow/fling and hook.