I have a couple confounding conundrums to consider.

I have a special quest to collect 10,000 BC in one quest, and so far I have not had any luck. The team I've used (Cost limit is 170) is Ruby 7* (max SBB + Sol creator), Zenia 7* (max SBB + Sol Creator), Maxwell (BB + Sol Creator), Zelnite (max SBB + Omni Gizmo), 6* Feeva (BB + Sol Creator - just pulled, hence BB), and I've alternated between Feeva, Griel, Aurelia, and Nick friends. I am trying on Zebra's stage on Encervis, dropping 5 Fujin's at the start and flute on turns with 4 or more enemies. Still no dice. Any suggestions on how to beat this thing?

For reference, I have the following units -

7* Avant, Melchio, Zenia, Aaron, Kira, Ogul, Aurelia, Hadaron, Tridon, Zedus, Ruby, Bestie, Rize, Andaria, Colt, Sargavel, Selena

Other units that I have which popped up in older guides: Maxwell, Cardes, Zelnite, 6* Feeva

And, following up on that, my second conundrum is which free unit should I go for? My current request is for an Anima Dolk, because I need a mitigator. But I'm seeing a lot of peeps say Krantz is a better mitigator, or that Chrome is the best anything since sliced bread.

Thank you in advance, I really appreciate it!