I already quit one character because he became an overpowered facerolling machine (sneak archer) and I really don't want the same happening again. I have read that illusion is overpowered and, coupled with conjuration, I can imagine even more so (cast summons, gather some monsters, cast frenzy, go make some tea). Has that been your experience?

Anyone? Bueller?

I'm doing an archer with illusion and conjuration, but that character is at a relatively low level (like 14 right now). He's powerful but not insanely powerful. Sometimes I do the tactics just right and don't get damaged at all, but I can also get killed if I go about a conflict the wrong way. I suspect it will get better as my level gets higher and I get stuff like summon dremora lord, higher sneak skill, etc though.

summons svck. Being a hynrid, at least at low levels, is much more difficult than it sounds.