Warhammer 3 has a quicker campaign now, thanks to the Champions of Chaos
If you're looking for a shorter alternative to Immortal Empires, this DLC is it.
My first time playing Realm of Chaos, the default campaign in Total War: Warhammer 3, I had a grand old time. As the daemon prince N'Kari I lured enemy units over to my side on the eve of battle while hopping in and out of interdimensional rifts like I was doing the Time Warp. Then I started a second campaign as Miao Ying, who plays quite differently—defending Cathay's Great Bastion while sending trade caravans out to deal with distant lands. Except that periodically the rifts would open again and I'd have to jump into the Realm of Chaos to fight the same battles I'd fought as N'Kari, then fight back the same daemonic invasions coming through them in my lord's absence.
Immortal Empires is one way of alleviating Realm of Chaos fatigue, letting you drop the whole storyline in favor of direct world domination. It's also a serious time investment, demanding you spend hundreds of turns yanking the borders of the map in your direction like you're fighting over a blanket with a partner who keeps hogging it.
There is another option. One that won't eat quite so many hours of your life.
Some of the DLC for previous Total Wars of the Warhammers included modified campaigns, like the Vampire Coast's quest for magical sea shanties to control a legendary beast. The Champions of Chaos DLC for Warhammer 3, which adds four legendary lords leading Warriors of Chaos factions, does the same. Its campaign follows on from the Realm of Chaos story: the rifts are closed, Ursun the bear god has quit his bellowing, and Archaon the Everchosen is preparing for war.
For my first campaign I pick Valkia the Bloody as my legendary lord. The Gorequeen serves Khorne the Axefather, and knows no chill. All her faction's armies get 15% extra movement on the overworld map after winning a battle, and her personal army gets a 35% movement bonus if an enemy retreats. She's relentless, incentivized to never stop fighting—her armies also get the same bloodletting effect as Skarbrand, earning buffs that decay if they stop fighting—and capable of crossing the map at outrageous speed.
That sounds like a perfect match for a horde faction, but the Champions of Chaos aren't hordes. They can settle anywhere, and if they take a settlement with a Dark Fortress in it (like the capitals of Norsca), they immediately vassalize a faction. My early turns as Valkia are spent besieging every Norse city within reach, rushing them with marauders and warhounds while Valkia flies directly at their general. One of her abilities gives her a window of invulnerability, so while she takes hits when it's on cooldown and the rest of the army hasn't caught up to her, this tactic literally never fails me.
Before long I earn some Gifts of Chaos, upgrades that include specialists added to a pool of gifted units that can be summoned directly into an army. All the Champions of Chaos are an army type called warbands, which means they recruit troops instantly and don't have to be in a settlement or even the recruitment stance to do it. However, which ones are available and how much they cost depends what territory they're in. You put out the call and marauders ride down from the hills and trolls lumber out of caves to sign up, no hanging around.
The Vilitch people
Another champion, Vilitch the Curseling, has a foothold on the western end of Norsca. He's a wizard who grows out of the back of his heavily armored conjoined twin in a way that's super gross. I thought the slimy daemons of Nurgle looked upsetting, but these guys are just wrong.
Since my gifted units include Bloodthirsters, greater daemons who are straight-up flying murder machines, I make pretty short work of Vilitch and friends. My mortal troops have leveled-up too, and that means I can upgrade them, giving armor to the trolls and turning the marauders into Chaos Warriors, as well as dedicating them to Khorne so they earn bonuses from my soaring Dark Authority score.
Finally, it's time to turn south. The goal of the Champions of Chaos is to earn souls, which are spent on Gifts of Chaos but also activate the dormant rifts scattered across the map. Instead of portals to the Realm of Chaos, once reactivated they become teleporters that let your forces appear directly in someone's face, then stab it. Open enough rifts and you can travel to the lost city of Zanbaijin, claim its altar, and officially declare yourself King Shit of Chaos Mountain.
The mortals of Kislev provide a solid harvest of souls. After field battles I get to choose whether to sacrifice the prisoners for souls, and after settlement battles the option to raze them notes it'll give more souls too. (The illustrations for these post-battle options, absent in Warhammer 3 at launch, have returned. Which is nice.) With tribute flowing in from my vassals and no need for settlements to recruit from, I'm free to go on a razing spree—pausing only to take Praag while I recuperate, though now I've got a second army to continue the rampage as I heal up.
We are the champions
The reason I need that breather in Praag is due to fighting a relatively tricky quest battle. Like all legendary lords, Valkia the Bloody earns unique magic items, including a shield wrapped in the face of a daemon of Slaanesh, via quests ordained as she levels up. These artifacts are worth having to take on a couple of enemies at once.
Regular lords and heroes in the Champions of Chaos roster are rewarded through Paths to Glory, conditions that give stat boosts or abilities when met. Winning a battle with two units of Chaos Knights in my army gives my hero vanguard deployment, and once he reaches rank five I can dedicate him to Khorne, though that means lowering his level. I figure it's worth it to get him access to my Dark Authority buffs, but if you don't want to go all out on one god you can have followers dedicated to others or plain Chaos Undivided if you like.
Soon I've got the souls I need to bamf to Zanbaijin and the final battle for the altar, holding it against all comers. Azazel, the Champion of Chaos devoted to Slaanesh, is first to attack, maybe because I'm carrying his mate's face around. I batter him with it, and then do the same to everybody else.
Though this battle's a drawn-out finale, I wrap up the campaign in just under 20 hours. On normal difficulty it's not been much of a challenge, which might be down to Valkia's starting position and blunt playstyle. The good thing about that is it leaves time to start another campaign as Vilitch the Curseling, whose magic-heavy focus and ranged units should play pretty differently. We'll see if I make it to the end of this one, but at least I got through one more campaign without having to go through the Realm of Chaos again.