Spoilers: Beast Pens and Bracchus. The pens are the campaign.

The Thousand Maws
Rakarth is Dark Elf Free-LC on the same ownership rows as Lokhir Fellheart. The February 2023 FAQ prints both names on the Warhammer II row and again under The Queen and the Crone and The Shadow and the Blade. The Thousand Maws fill the Beast Pens from battles, raids, and captures. The creatures on offer depend on what the campaign meets. An infantry core still has to win the fight before the next monster arrives.
Bracchus, his black dragon, is part of that identity. A dragon is large, so missiles and troops that are good against large creatures look for it. Dreadspears hold space around the beasts. Black Ark Corsairs pressure infantry. A Sorceress brings the magic. The pens are the reason to pick the fight. The monster that follows is the reward, and it still needs a line to land behind.
Fleet, ritual, and the Witch King
Lokhir is the fleet lord on the same Free-LC gate. His Blessed Dread grows Black Arks from major ports, and Update 7.0 points those arks at Aislinn's Eastern Colonies. Rakarth's reward for a battle is a creature in the pens, not a new ark. Malekith's Naggarond still uses slaves, loyalty, and the race's Black Arks. Hellebron's monsters, when she brings them, sit inside a Death Night army.
A beast taken in a raid is this campaign's recruit. The Sundering novels follow Malekith and Alith Anar. Rakarth's page is the beastmaster: which fight fills the pens, and whether the infantry can keep the new monster alive.
Rakarth: gameplay and availability · More character stories
Sources
- Immortal Empires FAQ, February 2023 — totalwar.com
- SEGA Immortal Empires DLC Ownership Guide — support.sega.com