Not that I disagree with how magic works in Skyrim in general, but Illusion/Conjuration/Alteration all work quite well. Illusion you have to pair with Sneak and dedicate your build to before it bears fruit, but its easily the most powerful school of magic even leaving aside how good stealth is. Investing in all the perks, being a vampire and dual casting spells let's you illusionify almost anything[Only the dumbest Falmer or Forsworn enemies are immune] and invisible sneak attacks handle anything that resists them.
The thing with Illusion though is it LITERALLY *STOPS WORKING* late game. As in I think it can't effect anything so many levels above your skill level or something, so when enemies level scale to ALWAYS be above that level, you are 100% shit out of luck. So you can go from being an unstoppable guile hero badass one level, and the next level your entire build is worthless.
Another example of this kinda thing is Fable 2-3 where the first level of magic lets you fling fireballs in any direction pretty much whenever you want, as quickly as you want, to the point you feel like a goddamn jedi, but then after foes level up a bit you HAVE to use the "stand around for 10 minutes charging" AoE modes to get anything done with magic.
As the game goes on you stop being a jedi and turn into a geriatric.
So yeah, this could actually be a related but separate peeve: Games where you feel more powerful in the beginning then you do late-game.
IIRC, the spellbook says that the caster is basically incapacitated until their skin is magically healed.
A prospective DM and I decided that it was possible for necromancers to swap skins. Cast Skinsend, have the skin pull itself over the other caster's body, cast Gentle Repose (spell that preserves corpses and body parts), return consciousness to actual body.
QUICK! GET JOHN TRAVOLTA AND NICOLAS CAGE! WE NEED TO FACE/OFF