What each type is for (support, offensive and amplifier), creating at the Altar, bond and Ascension Stars, branches and what the spirit does in battle.
Set the rules the Auto button follows: which skill to use, when to drink a potion and whom to hit.
How to unlock skills, equip the active ones and how long buffs last.
The damage formula, how defense works, elements, crits and area attacks.
How turn order is decided and which actions you have in battle.