[Chroma Eidolon Hunting]

So i have a couple questions to ask about this:
 
It this build good on rubico prime just for chroma ? https://imgur.com/hMVCucr
Should i get a primed cryo rounds?
What should i aim for on my riven?
What arcanes should i get ony my operator only for chroma?
Maybe that's a dumb question but i want to know if there's any way that arcane rage would be good. Cuz u know u need to stack up your combo on rubico anyway and you can headshot him for this arcane too?

Also i just want to make sure that this build is good : https://imgur.com/PiXikeD

[Primed Cryo Rounds]

The only thing that happened to this mod is that it dissapeared from my inventory and this happened to 2 of my friends aswell. And yes i did search for it on my sentinel and mods 

http://prntscr.com/mbmdux