Mage/Dark Wizard Help Improve this Pure build?

I need help improving this Pure arcanist build. I'm mainly looking to help it sustain better, as right now I'm having some difficulty with that.

https://hppeng-wynn.github.io/build...0Ji0Ql0p0p0r0o1Q1g000000z0z0+0+0+0+0-llbFFF-2
WynnBuilder build:
> Morph-Stardust
> Wanderlust
> Dark Shroud
> Violet-Shift
> Summa
> Summa
> Vortex Bracer
> Contrast
> Pure []

Non-negotiables
-Pure
-Entropy (preferably violet-shift, but am open to lachesism)
-100+ walk speed
-Full arcanist tree (no winded)

Preferences
-20k+ ehp before tomes
-meteor sustain (either high mana regen or very cheap meteors, or both)
-decent damage (25k+ meteor before tomes)
-no crafteds

 

summa -> photon for walkspeed? idk