Brave Frontier

^ Ditch Phoenix and farm a free healer (Claris/Amy). You lose a bit on damage but their burst heal is better. They're also easy to evolve and easy to max their BB. Also, creating Gilded Pearl spheres may help you survive. Typically they're only equipped on healers early game, but equipping 2 or 3 of your more fragile units with those spheres until you get your hands on >10% HP spheres might be worth it.

Elemental weakness does matter when your units are underlevelled, so do replace units that are weak to the dungeon's primary element. HP drops won't help you much if you don't have units with high hit counts, a single burst healer will work better. Aaand use Elza/Faris as leaders, that will make it easier to fill your healer's BB up.


Also, I don't know if anyone has mentioned it but I'd save my gems for the next rate up which will probably be Ulkina's batch. Summon when Narza's rates are up, since you'll need damage mitigation sooner or later. Every single unit in that batch are pretty good too, and two of them are healers so summoning then is very much worth it.

edit: scratch the gilded pearl thing. I forgot that by then you can craft 10% HP spheres, so Gilded Pearl for free healer and HP for other units.