What is Lunara's trait, Lunar Power?

Marks only pay out if you weave basic attacks between skill casts. Every skill or Ultimate loads four stacks, and each of the next four basic attacks spends one, hitting for 100% extra damage and healing Lunara a little. Lunara is a ranged DPS, so those empowered attacks land from range. The rhythm is cast, fire four basic attacks, cast again. Casting skills back to back without basic attacks in between wastes the stacks.

The healing is what shapes how Lunara plays. Spending stacks restores health and energy. That gives Lunara self-sustain in extended fights and cuts down how often you have to back off to recover. Together with ranged combat, it is why Lunara is the more forgiving of the two starters. Helion's trait, Solar Grace, runs the other way round: every fourth basic attack grants Solar Halo, which empowers his next active skill.

Not settled: How much HP each mark restores is not settled. It is given as both 0.01% and 0.5% of HP, and that gap decides whether the heal is a real source of sustain or barely noticeable.