Question what is the best way to fill your green bar to get the frosted protean crystals for the relic?

I just got level 35 and only had 5 Frosted Protean Crystal done with the green bar, but someone said relics take 31 right? I have 461 Pagos Crystal so I am close to the number needed there.

Not really understanding what I am suppose to do now or how you fill the green bar fast. Takes many NMs for just 1 bar.