god-mode sues make for boring stories because they banalise potential opportunities for interaction.
to wit, consider rumble, yordle mech pilot and ancient dragon simulacrum is certainly an odd pair, but the vaguarities of the league could allow two domineering personalities to create such a strange rivalry. cultural and mannerism differences would surely come up in interaction, beast and machine pitted in ever escalating conflict, either on its own or as an amusing side bar to other plots. mite b cool right?
nope, plagueiswinslol.
karthus, the death singer, ageless apparition of untold power and master of even death itself, who can say what motive he may have for ensorcelling a time-lost wyrm. perhaps gathering power for some quest or or military action, perhaps as insurance for some other ritual he plans to enact uninterupted, or maby even as practice for something more personal...
plagueis' A type mind-set would certainly chafe at even the hint of thralldom, and certainly the potential for internecine conflict is there, not even factoring what purpose the lich ultimately had. undoubtably the balance of power would be disrupted aswell, and many might feel threatened by such a turn of events, the protagonists (or maby even antagonists, whos to say...) might even take the chance of using the dragon as an enemy mine situation, playing the two off each other. the possibilities are endless, right?
nope, plagueiswinslol.
the dracoliches haughty and presuming foibles would certainly rub certain indivduals the wrong way, individuals that might not be crossed lightly, like the fallen angel for instance. plagueis may be brought into conflict with any manner of unsavory, but powerful persons, and in order to survive he may even be forced to foster allies of all things. perfect chance for potential character development, right?
nooope, plagueiswinslol!
ect, ect.
such characters usualy make for bad story telling because they prevent stories from ever happening in the first place, by there very nature, and you are forced to go to increasingly ridiculous lengths just to mearly involve them. yet even then, it can be hard to maintain interest in whatever is going on when its a foregone conclusion anyway (ie, plagueiswinslol), by then it all just feels meaningless.
at such a point your only options would be to portray the individual out of character inorder to facilitate a defeat, or concoct some kind of deus ex machina to provide a victory, both of which are in of themselves bad writing practices, which should hopefully also illustrate the problem.
from a purely aesthetic perspective, the only way such a character would have appeal is through ones insecurities and control issues, action without restraint for the feelings of repression. otherwise, it lacks ability to provide depth or fire the imagination, and marginalises the rest of the settings elements. to note, you certainly could have done alot worse with what you have, but it is also an ultimately self limiting concept.
thats my $0.02 anyways.