Spoilers: The Forge of Daith and the forest king's novel. No campaign outcome.

Heralds of Ariel
The Sisters of Twilight require The Twisted and the Twilight, a separate purchase from Realm of the Wood Elves. Naestra and Arahan are Ariel's twin emissaries and one Legendary Lord choice, the Heralds of Ariel. They fly and shoot. Victories earn Daith's Favour. The Forge spends it on crafted pieces, improvements, a temporary reforge, or a blessing.
Glade Guard and Tree Kin keep the ground battle. A Spellsinger, a Branchwraith, or a Waystalker covers the ground the air leaves open. A flying ranged lord is a target for missiles and for troops that are good against large creatures. The Forge's reward still depends on a battle the army can win.
A second pack on the same forests
Orion, Durthu, and Drycha remain the Realm of the Wood Elves lords. Orion leads Talsyn and the Wild Hunt. Durthu leads Argwylon. Drycha is free with that pack and fields Glamoured Elves. The Sisters keep the forests, the Deeproots, and Forest Health, and they add the Forge.
Owning one pack unlocks its lords. Realm of the Wood Elves does not include Naestra and Arahan. The Twisted and the Twilight does not replace Orion. A player who owns both still picks one campaign at a time. The Forge is this campaign's extra layer.
The forest king's books
The Vaults of Winter follows Orion. He sleeps in winter, returns in spring, and this year a curse sits in that cycle. He leads the asrai to war. The traitor inside the realm stays unnamed. The 2019 Warhammer Chronicles collection places that novel with Tears of Isha and The Council of Beasts.
Naestra and Arahan are the heralds of this pack. A crafted piece from Daith is a reward on their campaign. A Ritual of Rebirth is still the race's way of restoring a forest. The unmasking in the novel is the king's.
Sisters of Twilight: gameplay and availability · More character stories
Sources
- SEGA Immortal Empires DLC Ownership Guide — support.sega.com
- Orion: The Vaults of Winter — blacklibrary.com
- Warhammer Chronicles: The Orion Trilogy — blacklibrary.com
- The Twisted & The Twilight — store.steampowered.com