Fortify Destruction Potions + Cloak = Fun

The exploited potions increase range, as well as damage.

[anomanomom]

You don't really have to do restoration cheat or wear daedric armor to kill enemies without inflicting direct damage.

Learn conjuration and invest into necromancy. Invest into necromage perk, find bloodworm helmet and bone wolf pet. Learn dead thrall spell, etherealness shout and dragon skin spell. Find and kill a pair of vampire lords or archmages to turn them into thralls (by abusing weaker thralls or dremoras at first)

Once you have those you can abuse a pretty fun strategy:
When the fight starts you shout etherealness. That gives you a few seconds of invulnerability and allows you to channel dragon skin without it's main flaw. Hold the dragon skin channel and release it when etherealness finishes. Prepare healing spell and leisurely heal yourself if health drops a little while dragon skin is active. In the meantime a pair of vampire lords/archmages would machine gun whoever is fighting you with adept and expert spells while you barely receive any damage. By the time dragon skin fades your etherealness would be ready to repeat the combo.

Become ethereal shout generally turns master level spells much more powerful by removing the whole "vulnerable while channeling" disadvantage. Pretty sure developers expected players to use them that way (cause you get that shout during college questline), but the playerbase wasn't smart enough to understand it.

[azzor]

i didn't know fortify destruction increased both range and damage. too bad you need exploits to make it good, because a 220% (around the max you can get without exploits) fdestruction potion won't be enough on legendary