I hope someone from developers will hear this. Malkoran from the Meridia quest:

1. Instakills a character of 330 HP with a single frost attack;
2. Deals frost damage through 130% frost resistance (Shield of Frost Suppression 50%, Necklace of Waning Frost 30% and block Elemental Protection perk 50%)

What does he cast to instakill? Regardless, unreal scripted damage ruins immersion. Lame.

It's Frost Storm. It's a spell you can learn too.

Silly, you can only get resistance up to 85%. And, Frost Storm is evil evil evil. Evil.

I see. Thanks. Did anyone try to cast frost storm back at him? Does he die? What would be the best way to kill him?

Yeah, although you seem to have more, resistances cap out at 85%. Including the physical from armor (Armro ratign 580something)

You can combo Spell Absorption, Magic Resist and Frost Resist to nullify that sort of thing down a lot though.

Outside of that, Fortify Health, or get a Greater Ward up (it'll break, but should cancel the damage from that attack). Or stay out of the room and cast Frost Atronachs in.