Mournful Witch·Serena

Mark 3 targets, and deal Fire DMG to them over 1, 3 and 9 hits respectively.
When the marks are active, for each of their skill card used, increase their Fire DMG taken by 10%.

Generate 3 [Phantom Happiness] in your deck.
[Phantom Happiness]: Deal Electro DMG to a random ally once and grant Serena 10 Energy. This card is [Destroyed] when used.

Deal Frost DMG once and inflict [Starbind].
[Starbind]: Reduce ATK by 30%. When an ally uses a skill card, move this effect to them, deal Frost DMG once and inflict [Chill] to them. This effect expires after moving 6 times.

Summon the falling stars. Consume all [Radiance] stacks and apply equal [Flaw] stacks to allies in range. Deal Reverb DMG to them once and randomly inflict [Imprison], [Fetter], [Curse] or [Confuse] once.
For each [Perpetual Reincarnation] cast, inflict the above negative effects once more.

DMG: 3200% Reverb

Gain 1 stack of [Radiance] every 10 seconds.
When a card enters your hand, reduce its Cost by 1, and apply 1 stack of [Flaw] to the card holder. If the Cost becomes 0, apply 1 stack of [Radiance] to Serena.
When you use a card, remove 1 stack of [Flaw] from the card holder.
[Radiance]: Increase Max HP by 1%. This effect stacks.
[Flaw]: Reduce Max HP by 1%. This effect stacks.

After casting [Finale·Starfall], draw your cards to a full hand, and Serena will cast [Eternal Farewell], [Phantom Happiness] and [Restrained Dote] sequentially.