Mage/Dark Wizard Help with endgame fatal build

https://wynnbuilder.github.io/builder/#CN0dp0-CWi3wtW10C0Wu2QdmecBUWm08-VhjTNF3
> Wynnbuilder build:
> Third Eye
> Time Rift
> Aleph Null
> Pro Tempore
> Summa
> Summa
> Megabyte
> Contrast
> Fatal [t6t6t6]
> (Has Tomes)
Annoyed with using runebound chains (spell costs) and want to play rift (i know its bout to be changed ignore that) so I built time rift.

This isn't optimized and ws/ehp/maybe damage could be improved. Also I'm not sure why all the mythic riftwalker builds I see have 0 sustain (manastorm is only -5 at best) but feel free to take away from sustain as long as you can still do 9-12 cps

 

I found vaward can be pretty good here (not as much damage as aleph null, obviously) but the overall everything but sustain still lacks a bit, I just don't know how to translate sustain without sacrificing too much