So is the best strategy when you've built up a shitload of cards to combine as many as you can, then feed the commons to the uncommons, those uncommons to the rares, the the rares to the ultra rares (if those are your playables)? Should I wait until I, say, max out an uncommon before feeding it to a rare because that seems super grindy and tedious.
Also I maxed out my common Tamina and still no better Diva card in sight. I guess I'm stuck with her.
I don't bother maxing out any cards I'm going to feed. Just pro them if I can then give them to the one I'm training up. Served me well so far.