Spoilers: The guild disasters and the novel's first appearance. The battle at Karag Dum is left where the jacket leaves it.

Who he is in Total War
Malakai leads the Masters of Innovation. Malakai – Thrones of Decay unlocks him, and Garagrim Ironfist, for Immortal Empires and for a Realm of Chaos campaign with its own objective, apart from the Ursun story. Creative Assembly's introduction says he was in the Engineer's Guild, built the ironclad Unsinkable, which sank, and the airship Indestructible, which blew up. Those failures cost dwarf lives. The guild ejected him, and he took the Slayer oath.
In battle he is a ranged support lord: guns, bombs, and artillery, kept near the missile line with infantry on the approaches. The Slayer oath is not a reason to abandon the machines. Adventures turn reports of hard enemies into expeditions that upgrade the Spirit of Grungni. The store page says he still hopes for a glorious death that would leave him remembered as an inventor. That hope is the character's. A campaign does not have to grant it.
Two airships
The Spirit of Grungni is the game's ship. The introduction says it was first used to evade Skaven forces that struck Wissenland, and that it ferries supplies, supports recruitment and infrastructure, and can be called into a battle. Adventures improve it. That name and that career belong to the Thrones of Decay campaign.
William King's Daemonslayer is book 3 of the Gotrek & Felix novels. The jacket sends Gotrek and Felix north toward the lost hold of Karag Dum in an experimental dwarf airship captained by a Slayer-engineer. Black Library's reading note says Malakai Makaisson, Ulrika Magdova, Snorri Nosebiter, and Max Schreiber first appear in this book. Malakai is the engineer on that voyage. The jacket does not give the airship the game's name, and it leaves the battle at Karag Dum unresolved. Ulrika is alive in this book. Her later turning is Vampireslayer, a different novel.
Engineer, runelord, and slayer king
Thorek's anvil and relic grudges are the old craft. Malakai's adventures are the new machines, built after the guild expulsion. Ungrim is the Slayer King at Karak Kadrin, and Garagrim is Ungrim's son, recruited into an army through his own mission once the Malakai pack is owned. Thorgrim's Book still records grudges for the whole race. Belegar's war is Eight Peaks. Grombrindal's Age of Sigmar novels are the Mortal Realms, not this airship.
Daemonslayer is the novel that names him. The guild ships and the Spirit of Grungni stay labeled as the game's machines. A player's adventure route is not the expedition to Karag Dum unless the player is simply borrowing the idea of an engineer who will not stop building.
Malakai Makaisson: gameplay and availability · More character stories
Sources
- Immortal Empires DLC Ownership Guide — SEGA — support.sega.com
- Thrones of Decay: Introducing Malakai Makaisson — Total War — totalwar.com
- Malakai – Thrones of Decay — Total War — totalwar.com
- Daemonslayer (eBook) — Black Library — blacklibrary.com
- Immortal Empires DLC Ownership Guide — support.sega.com
- Malakai – Thrones of Decay — store.steampowered.com
- Thrones of Decay: Introducing Malakai Makaisson — community.creative-assembly.com