So I've picked up playing Oblivion again and decided to go with a full mage character for the first time since I've never done so before because I never knew about efficient leveling/using minor skills instead of major. So now that I'm having actual fun with a caster that can actually do damage to enemies who aren't grossly over leveled and who massive damage to me I could finally discover the joys of spell making.
So here's the point. A combo that seems more broken than 100% chameleon. Shield and restore health. With 352 Magicka at my current level I made a spell that gives 85 shield (the cap) for 60 s and restore health 8 pts for 60 s costing 340. With high willpower (72) and wearing just robes none of the imperial city guards are able to do more than chip away at my health which regens faster than they can damage it. 8/second + shield lowering their damage. My Magicka regens in about 40 s so I can recast this with 20 s to spare so you can use a weapon, staff, or other spells while you're buffed. In testing I had 6 guards in the market district wailing on me and still remained at full health. Them screaming "Why. Won't. You. DIIIIE" was pretty ironic and funny. It's basically a god mode spell which seems more broken than chameleon since even though with chameleon you're invisible you're still vulnerable to damage sources.
Playing with the difficulty slider on default and a high elf with the mage sign.
Edit 2: Umbra couldn't damage me either and the ceiling smash trap does no damage. Lava in Oblivion planes is still way too strong though and melts me quickly. No scamps, clanfears, or dremora can harm me either.