Spoilers: Game cult and the Malekith novel's jacket. No campaign outcome.

The Cult of Pleasure
Morathi comes with Total War: Warhammer II and leads the Cult of Pleasure. The February 2023 Immortal Empires FAQ lists her with Malekith on the Warhammer II Dark Elf row. The cult spreads Slaanesh corruption and can field certain Slaanesh units. Slaves and construction still sit under that system. She is the sorceress. Dreadspears keep a screen. Black Ark Corsairs take a flank once the line is holding.
Naggarond is Malekith's other Warhammer II campaign. Har Ganeth is Hellebron's later Queen and the Crone campaign. Choosing the Cult of Pleasure means watching corruption and the slave stock together. The spears still have to be in place before the expensive cast lands.
The mother in the Sundering novel
Gav Thorpe's Malekith is a Time of Legends novel and the first book of The Sundering. The jacket says the prince is passed over as king. His mother Morathi goads him. The cult of pleasure is the pretext. He betrays Phoenix King Bel Shanaar, and the civil war that follows is called the Sundering. Malekith is the protagonist. Morathi is the mother who pushes him.
The play page already calls her Malekith's mother and a longstanding architect of his rule. That is the same family the novel uses. The cult on the jacket is a pretext inside the civil war. The corruption meter on the Cult of Pleasure is the campaign. An alliance between mother and son on the map is a choice the player makes.
Hag Queens, and a later march
Hellebron's campaign treats the struggle between the Hag Queens and Morathi as a rivalry for power. Death Nights and the Blood Voyage belong to Har Ganeth. The Queen and the Crone sells those two queens as one pack and two campaigns. Lokhir and Rakarth can also unlock from a Dark Elf purchase, and their wars are the fleet and the Beast Pens.
The Curse of Khaine follows Malekith out of Naggaroth toward Ulthuan and names Tyrion as Regent. That End Times book is his march. Morathi's place in the fiction used here is the mother in the Sundering novel, beside the Cult of Pleasure she leads in Immortal Empires.
Morathi: gameplay and availability · More character stories
Sources
- Immortal Empires FAQ, February 2023 — totalwar.com
- Malekith (eBook) — blacklibrary.com
- Malekith extract — blacklibrary.com
- The Curse of Khaine — blacklibrary.com
- Immortal Empires DLC Ownership Guide — SEGA Support — support.sega.com