How does Helion's Solar Grace trait work?

The rhythm is four basic attacks, then an active skill. The fourth hit is what charges it. Solar Halo goes onto the next active skill you cast, so a skill fired off before that fourth hit lands goes out without the bonus.

The charge builds as sun rings while you keep attacking. Landing hits also raises the power gauge of the attack that follows. The trait rewards you for staying in contact with the target rather than stepping back between swings.

That fits what Helion is: a close-range physical DPS built for burst damage and aggressive combos. His ultimate transformation amplifies the damage of his other abilities, so Solar Grace and the ultimate push toward the same goal. Both make his skills hit harder, and his biggest bursts come from lining them up.

Helion vs Lunara: how the traits differ

Lunara's trait, Lunar Power, runs the loop the other way round. Casting a skill or Ultimate gives her four stacks of Silver Moon Mark, and each basic attack spends one stack to deal 100% extra damage and restore some HP. Helion's basic attacks feed his skills. Lunara's skills feed her basic attacks.

The two starters share mirrored stats, the same Light element and the same DPS role, so this loop is one of the real differences you feel in play. Helion's version asks you to keep swinging at close range. Lunara's gives her sustain for longer fights from range.

Not settled: The Sun starter also appears under the names Elion, Caelion and Halcyon. Solar Grace is the trait of that same creature, whichever name you see.