Spoilers: The Daemon's Curse jacket, and Deathblade's End Times question. The jacket leaves the choice open.

Hag Graef and possession
Malus requires The Shadow and the Blade. The pack unlocks Hag Graef on its own, without the Warhammer II base game. The February 2023 FAQ lists him on that pack and lists Lokhir and Rakarth as the Free-LC names on the same row. Possession is the campaign. Elixirs hold Tz'arkan down. Giving the daemon more influence changes the balance. In battle he can loose the daemon.
Dreadspears and Black Ark Corsairs still have to win the infantry fight around him. The Master hero from the same pack is a different action from selecting Malus as the lord. A possessed lord is a risk in the duel and a liability if the line behind him has already broken.
The Daemon's Curse
The Daemon's Curse is book 1 of the Chronicles of Malus Darkblade, by Dan Abnett and Mike Lee. The extract's title is The Daemon's Curse. Malus leads an expedition into the Chaos Wastes. He is possessed by the daemon Tz'arkan. The quest that follows is to save his soul. The ebook page calls the possessor a powerful daemon. The extract names Tz'arkan.
Malus is the protagonist. The Hag Graef meter, with its elixirs and its whispers, is the campaign's use of that possession. The expedition in the novel is the start of the series. A player's raid on the campaign map is not that journey into the Wastes.
Deathblade, labeled as the End Times
Deathblade, by C. L. Werner, is book 6 of the same series and an End Times novel. Malus is ruler of Hag Graef and a general of Malekith's armies. Malekith orders an assault on Ulthuan with Darkblade in the vanguard. The stake on the jacket is whether Malus follows Malekith or tries for the throne of Naggaroth. The jacket poses the question and leaves it there.
Malekith is the Witch King who gives the order. That assault is End Times fiction. It is separate from the Hag Graef opening, and separate from the first novel's expedition. A campaign that reaches Ulthuan is the player's war.
The jacket's question
Deathblade's blurb stops on the choice between Malekith's order and the throne of Naggaroth. The assault's result stays inside the novel. A Hag Graef campaign is a separate war.
Malus Darkblade: gameplay and availability · More character stories
Sources
- Immortal Empires FAQ, February 2023 — totalwar.com
- The Daemon's Curse — blacklibrary.com
- The Daemon's Curse extract — blacklibrary.com
- Deathblade — blacklibrary.com
- Immortal Empires DLC Ownership Guide — SEGA Support — support.sega.com