Gear:

x5 Twice-Born Star (includes weapon with either infused or nirnhoned)
x4 Martial Knowledge (cheapest armor piece with rings and necklace) {eventually can be moved to a trial set with monster damage}
x2 Valken Skoria (This preferably in medium and heavy or 2 heavy and Divines)

Armor Traits:
Divines

Weapon Traits:
Infused/Nirnhoned/Precise
(all are acceptable choices)

Enchants:
Magicka for armor
Flame for 1st bar
Weapon Damage for 2nd bar

Jewelry Enchants:
(Non-Vamp) x2 Mag Regen & x1 Spell Dam
(Vamp/ High Elf) x1 Mag Regen & x2 Spell Dam

Mundus Stones:
Thief(crit chance)/ Shadow(crit damage)/ Apprentice(spell dam)/ Mage(max magicka)

So the idea behind this is to proc Valken set with keeping up your dots. Also make sure to keep up the buffs from merciless resolve and degeneration. If you run with someone that's a dragonknight who uses Molten Weapons and it's morphs, then drop degeneration and use Refreshing Path(RP). RP is a great dot/ heal/ getaway utility skill. This build requires some bar swapping. You have on your back bar your mana regen/ resistance debuff (Elemental Drain) also includes Siphoning Attacks. Last, but not least, you have your execute ability (Impale). When the boss drops down to 26% health get your buffs up and then start spamming Impale at 24% and below.

I supplemented my magicka regen by vamp passives. However completely valid to not use vampire with this class. It does help however to be a Dark Elf for the 7% extra fire damage, but High ElF Works just as well which gives Mag regen and 4% fire damage.