Maya explains chaining the first time you land one

Chaining is one of those things that clicks the moment someone shows you, so now the game does. The first time you pull off a chain bonus in an ordinary fight, playback pauses and Maya walks you through the rule: the cards have to line up in tracker order, on the same turn, against the same enemy.

She also spells out the payoff — a plain chain adds extra damage, while chaining effects instead feeds you energy back or healing. It's a one-time thing; once you've seen it, it never interrupts again.