I have found that in LoL one of the easiest things to do is tank. You may not be uber kill monger, but done right you can be an uber assist machine! Taking the place of a carry, or a melee death dealer, you as a tank are there to stop aces, and to hold off so someone else can live. Sure you can do things that will add the damage up, and with Leona you can really dump in the CC this is the tank of all tanks. IMHO.