I would love if Vampire Counts was added. Lore wise it make no sense because Vampire Counts and Chaos are enemies. But at the end of the day it is just a game and they do not have to join chaos, it will just be another enemy. I mean Beastmen killed a rat ogre in the Dark Omen map.
A post in February had some nice suggestions, Link. Another idea could be that the dlc only adds new specials and not basic units like zombies, skeletons etc.
Necromancer - Spawns like a Blightstormer, are guarded by two Wight Kings and raises all dead enemies around you. They are zombies, their attacks and movement are slower & do less damage. Killing the Necromancer will make all the zombies die. The problem here is that corpses do not stay on the ground so this might not work.
Vampire - Monster. A Blood Dragon Vampire, there are some famous ones, Abhorash & Walach for example. But Blood Dragons are mostly traveling the world seeking out worthy opponents to fight. It is said that Abhorash are one of the few Vampire to cure himself from the need to drink blood.
By slaying and drinking the blood of a Dragon. He told his bloodline to travel the world and seek out worthy opponents so they also could cure them self from the curse.
Fell Bats - Like the Packmaster they grab you and fly away and drop you, unless someone shoots it down. You still take fall damage if it is killed.
Vargheist - Monster.
Crypt Horror - Monster.
Bansjee - Grabs a player and damage them, every player is also slowed because of her scream. Or she just screams and all players take damage and/or are slowed.
Fatshark could also make a Vampire Counts dlc with new maps. A side story where the heroes have to stop the Vampires from doing something horrid. It could be only Vampire Counts enemies on the maps.
Let’s say a powerful Necrarch Vampire are going to raise an army from an old battlefield, the heroes must stop him. But he is not alone a Blood Dragon and a Strigoi Vampire have joined him.
First you face the Strigoi Vampire, the boss fight could be basic. He is fast and fight like a Berserk. Stagger is not that strong against him, you can stagger him with bombs & abilities but the stagger time is mush shorter on him.
During the fight Ghouls and Crypt Horrors spawn that you have too deal with and during that time the Strigoi falls back and regenerate health until you have killed all trash that spawn.
The Blood Dragon is next, they are really weak when it comes to magic but few things in the warhammer world come close to them in close combat.
He would be armored, have a two handed sword and his attacks would cleave and if you are hit you fly back. He can so a “teleport” move.
The animation could be that he is charging an over the head attack then teleport in front of one player and after 1-2 seconds he brings the sword down. The attack can’t be blocked and if you are hit you will go down. To avoid it you have to dodge to the side.
A mechanic could be that block is not as good against him, some damage always go through so the best option would be to dodge. His attack animations would instead be slow like Bödvarr.
Necrarch are powerful magic casters. This fight is a lot of trash, Zombies and Skeletons. He have two spells
Curse of Years - Like Burblespues Pestilence Possession attack it possess the player and you lose Stamina & health for each tick. Attacking the Vampire stops the spell.
Gaze of Nagash - Shoots 3 projectiles towards the player farthest away from him and damage the first things it hits.
Skaven and Chaos could be on this maps and the story behind it could be that they are trying to claim what ever the Vampire Counts are up to. Or you just run in to them on some fixed places, for example, you could run in to Beastmen in woods, Skaven underground and Chaos close to water.