Congrats. You've been working on this for long time.
Usage of tp is really good idea there, because usually when you try it, start of the fight is rather smooth, slow, ow, and then get some damage, this usually works, until he starts casting and you have problem surviving. So you can basically "reset" the fight and keep repeating that in short segments. Gives you some time to rest as well.
I also like use of deathgaze, I assume this causes less struck procs than for example iceburst, so you pack more damage per hit, which is desirable. There is also boss hitbox which probably works better with skill such as deathgaze, it seems to deal better damage vs small bosses than stormblast and clones.