I'm using Salsa, March, and Frederic, for the attack and def boosts. But not sure how you use Harmony Chains.
You get Harmony Chain at Party Level 4 which is after you beat Fugue. D=
I beat him, I know I have the Harmony Chains, but dont know how you use them.
Almost the same way guard works, if you have at least 24 echoes and you do a special, Harmony Chain will flash then you press the special button and you get another special from an ally that is in range. You can chain up to two at party level 4, three at 5, and six at 6.