Helwalker/Ascendant. (monk/cipher). For weapon use Essence Interrupter, which you can buy at Port Maje.
Max Per, Int, Might. Dump Res.
In battle, get 10 wounds quickly either from Dance of Death or getting damaged. You'll build up focus fast with Essence Interrupter and Hunting Bow Modal (fires twice as fast). Armor's not a problem because Essence interrupter is Pierce/Shock. Any armor that blocks pierce is vulnerable to shock. Get Turning Wheel's +10 Int bonus. Get +10 Might Bonus as Helwalker. You'll be sitting on 35 Might and INT if you add in equipment and food bonuses.
This means that when you ascend you'll have almost a full minute of ascension time for free cipher spell spam.
While ascended, spam 35 MIght, 35 INT disintegrates on dragon.
Fight ends quickly.
EDIT: If you need someone to tank, stuff a herald or two with their summons in front of her (paladin/chanter-troubadour). Heralds can tank everything in the game since they can heal, summon, and have insane defenses.
Edited by Marigoldran, 17 April 2019 - 04:14 AM.