In Dragon Age, I made a primal mage with the Spirit Healer and arcane warrior specializations, maxed out both of those, and maxed out every part of the primal spell tree as well as some parts of entropy. The result was a very nearly indestructable warrior-wizard who could wear even the heaviest armor with more or less no penalty, charge headfirst into a mob of enemies and come out with nothing but a scratch, and at range could destabalize, paralyze, blind, and otherwise destroy anything that looked at him funny. That game was a breeze after that.
I also made a "ninja" class in Oblivion, which specialized in blades, acrobatics, lockpicking, sneaking, speech, light armor, and some other thing I don't remember. It KICKED ASS.