I have everything else ready to Awaken my betty (To use for gold farming.) All I need is the orb.

I was attempting to follow this video guide: https://www.youtube.com/watch?v=OJ00A0NNtf4 . I have the right units leveled and ready to go, but I don't have them CR'd to the point that I can do this, invariably some of the mobs slip past or worse the mages will kill my 2nd archer before i can get the healer out. Any tips?

I have mostly silvers with the latest few event units.. my gacha luck has been iffy with no plats (Besides free ones) and no blacks. I've got a few golds: 2 Bettys, fedora, Robert, Themis, Zola, Mehlis, Iris, Vincent (and the 2 free ones)