Excellent build man! Just one question, why did you choose to use necromancy as opposed to using atronachs? It just seems a bit weird from an RP standpoint when you use holy-esque weapons like dawnbreaker. Other than that +1.

The last screenshot is badass! 

I love this build, it's simple and effective. Keep up the good work lovin' yer builds .

For Azura's light, could Firey soul trap and Drain Magicka work better? :)

I prefer Damage Magicka over the Absorb Magicka effect, it has a lot more uses and saves on recharging. Fiery Soul Trap would be a good choice but the Ascendant can use the Soul Trap spell instead which also levels his Conjuration. You would get a lot more charges with Fiery Soul Trap though, and you would always have soul gems to refill it when needed.

I chose Necromancy because the Dunmer seem to be more skilled in the darker forms of magic, and even a heroic character would be willing to raise corpses to help him fight against evil. I saw it as giving the raised dead a "second chance". Of course you could use Atronachs, but the most fitting one, the Flame Atronach, is also the weakest whereas raised corpses can be up to around level 30, which allows you to raise most enemies.

I made an account and waited three days for it to be verified just to like this build +1

Mythic! 

Is there any other race options? I can't justify a dark elf being dragonborn to myself