Building a well-balanced team

A team’s core is its kamihime.
Weapons, eidolons, and upgrade materials can be farmed from events, but kamihime selection is mostly determined by the luck of the draw in Gatcha. Until the introduction of 100% elemental attack bonus eidolons, kamihime selection will determine a team’s potential. Soul selection will fill in the necessary gaps in capabilities.

A balanced team should include healing, ATK/DEF debuffs, and spike damage.
A balanced team with two sources of healing (~400 healing/turn), -32% ATK/DEF, and sufficient spike damage/mode reduction to deplete the Rage meter without Burst (ex: damage skills totaling 10x damage) will be sufficiently versatile to deal with a wide range of challenges.

ATK and DEF debuffs scale exponentially.
Each additional percentage point provides more benefit than the last. Increasing DEF down debuff from -40% to -50% increases damage by 20%, nearly double the benefit of 0% to -10%. Players should strive for -40 to -50% ATK and DEF down when possible.

Debuff priority
DEF > ATK > Overdrive extension > Overdrive reduction > Debuff resistance down > Combo attack down > Blind > Triple attack down > Double attack down > Paralyze > Charm > Stun extension > DoT
This priority scale is meant only as a general guide, and does not cover all situations. The relative usefulness of overdrive gauge extension / reduction, Blind, and attack frequency down will depend on the threat posed by a boss’s normal attacks vs. its overdrives. Also, some skills in the same category have stronger effects and/or accuracy than others.

Certain skills are situationally useful, and even mandatory for certain encounters
Many encounters will require overdrive gauge extension to make punishing overdrives less frequent. Certain bosses have powerful buffs that must be dispelled. Others use debilitating debuffs that must be cleaned. Use Soul EX abilities to cover these needs as required.