Guide
How the kit works
Before a fight, use Saunter in the Rain to give everyone Invigoration for 2 turns at the start of the next battle. Gourdful of Elixir makes Invigoration heal an ally after they are hit. At the listed values, it restores 5.4% of Bailu's Max HP plus 144 and can trigger twice. A passive grants one more trigger, while another makes characters with Invigoration take 10% less DMG.
Use Singing Among Clouds when an ally needs immediate help. It heals the chosen ally for 11.7% of Bailu's Max HP plus 312, then heals random allies twice. Each successive heal restores 15% less than the previous one, so you cannot choose where the extra healing goes.
Felicitous Thunderleap heals the whole team for 13.5% of Bailu's Max HP plus 360. It applies Invigoration to allies without it and extends existing Invigoration by 1 turn. Invigoration normally lasts 2 turns and cannot stack. The Talent also prevents one teammate's knockout per battle, healing them for 18% of Bailu's Max HP plus 480 after a killing blow.
When healing is unnecessary, Diagnostic Kick deals Lightning DMG equal to 100% of Bailu's ATK to one enemy. A separate passive increases an ally's Max HP by 10% for 2 turns when Bailu heals them above their normal Max HP.
Build and why
For relics, start with four pieces of Warrior Goddess of Sun and Thunder. Two pieces give 6% SPD. After Bailu heals an ally other than herself, the four-piece effect gives her 6% SPD and the team 15% CRIT DMG for 2 turns. Messenger Traversing Hackerspace is an alternative: it gives 6% SPD and, when Bailu uses her Ultimate on an ally, gives the team 12% SPD for 1 turn.
For the planar set, Giant Tree of Rapt Brooding gives 6% SPD. At 135 SPD it increases Outgoing Healing by 12%, rising to 20% at 180 SPD. Fleet of the Ageless is another option: it gives 12% Max HP and, at 120 SPD, gives allies 8% ATK.
Use Outgoing Healing Boost or HP Percentage on the body, SPD on the feet, HP Percentage on the sphere, and HP Percentage or Energy Regeneration Rate on the rope. For substats, prioritize HP Percentage, then SPD, then Effect RES. HP improves Bailu's healing, while SPD helps her reach the planar set thresholds.
Night of Fright is the first weapon to consider. It gives Energy Regeneration Rate, heals the ally with the lowest HP percentage when an ally uses their Ultimate, and grants ATK to allies Bailu heals. Time Waits for No One gives Max HP and Outgoing Healing, then turns recorded healing into Additional DMG when an ally attacks. For a four-star option, Post-Op Conversation gives Energy Regeneration Rate and improves her Ultimate's healing.
Leveling priority
Follow the game's order: level Felicitous Thunderleap first for team-wide healing, then Singing Among Clouds for targeted healing, then Gourdful of Elixir for Invigoration and its emergency save. Level Diagnostic Kick last because damage is not Bailu's main job.
For maximum ascension, you need 308,000 Credit, 65 Lightning Crown of the Past Shadow and 15 each of Extinguished Core, Glimmering Core and Squirming Core.
For all skills, you need 3,000,000 Credit, 8 Tracks of Destiny, 18 Seed of Abundance, 69 Sprout of Life, 139 Flower of Eternity, 12 Guardian's Lament, 41 Extinguished Core, 56 Glimmering Core and 58 Squirming Core. These skill costs are separate from ascension.
Eidolons worth it
Evil Excision is a good upgrade to consider for team damage. Each heal from Bailu's Skill makes its recipient deal 10% more DMG for 2 turns, stacking up to three times. The random extra heals still decide where those bonuses go.
Drooling Drop of Draconic Divinity is worth considering if you want another safety net: it lets Bailu save an ally from a killing blow one more time per battle. Sylphic Slumber is a healing option, giving Bailu 15% more Outgoing Healing for 2 turns after her Ultimate.
You do not need to aim specifically for Ambrosial Aqua: its 8 Energy only goes to an ally whose HP is full when Invigoration ends. E3 and E5 raise skill levels, so you can also treat them as steps toward later Eidolons rather than targets on their own.
Teams
Remember that Bailu's listed skills do not remove debuffs. Against enemies that apply troublesome effects, consider what the other team slots need to cover.
Common mistakes
Do not rely on the random heals from Singing Among Clouds to reach a particular second ally. Choose the ally who needs the first heal most, then use Felicitous Thunderleap when the whole team needs recovery.
Do not assume Invigoration stacks when you use the Ultimate again. It extends the existing effect instead. Keep track of the Talent's limited killing-blow save too, especially in a long battle.
Avoid building ATK for healing: Bailu's listed heals scale with Max HP. Check your SPD before counting on the thresholds from your planar set, and remember that the once-per-battle save does not replace a way to deal with debuffs.
