But! Got Elise, Benny, and Charlotte to 20 the map after they joined in doing so.

So pretty damned worth.

What map and what difficulty?

Maybe I could do better in Conquest if I knew where to safely grind, because I'm still screwing up even in brE.Z. Phoenix mode in some ways, like underleveled units

Revelations 15. Hard. Easy enough map, I was just slow grinding it for the lot of them.