I suggest using:
5 Crimson Archon Shards with ability duration, so you can get 300% ability duration and 90% damage reduction on 1. (also more particles past 18 wont grant more damage reduction, but allows you to have room for losing and gaining new particles without losing damage reduction, which is good)(the wiki also shows wrong amount of null stars with given duration.)
^
(Old Build Below + 1 less Umbral Forma):
If you don't have those, you might want to swap [Adaptation] for [Augur Message] and [Umbral Intensify] for [Constitution]. (Thats how the build looked at 22 upvotes and 4 comments, but I decided to change it since I want to optimize and take advantage of the Archon Shards)

-range so you don't lose the particles from 1 fast (they seek out and hit enemies, which makes you lose them), 2 and 4 are not affected by the -range (only explosions from when enemies die with 4 on them is affected, but this damage is so minimal that it really doesn't matter, how far 4 goes out is determined by duration)

ABILITIES:
With Eclipse the -range doesn't matter at all, I do like the portals, they are fun, but Eclipse gives a massive damage boost, especially when hitting 2, you can make a 15m explosion that damages MILLIONS :O and Eclipse also isn't affected by range.

Max amount of particles on 1 giving 90% damage reduction when all flies around you, new particles from 4.

MODS:
([Guardian] actually provides more EHP than [Adaptation], even at max stacks I think from my Simulacrum testing)

ARCANES:
Molt Reconstruct might be better than Arcane Grace if you don't have Arcane Grace maxed or depending on your playstyle.

Speedva compatible build: Speedva

Enjoy!