Not 100% my build. I found some on the page and make a good pairs.
I dont use the fully Umbral and Primed version of the mods so I only needed 2 umbral forma, but you will need a 3 for the full one, mostly for the primed continuty.
The new augment lets you use your 4th "infinitly" So its nearly like an old [Ember] with her 4th, back in the days.
Good for exterminations and running everywhere, I use this for a long run (I mean 1h) in the new mars Def(mirror)
Archons:
2 Casting speed (1if u use Tau)
1 Streng
1 Duration
Last is yours