My VC legendary campaign went like this:
1. Starting out, trying to get the best of everything. Game takes 200 turns just for me to try and even put a dent in Dwarfs. Let alone anyone else.
2. Gave up, just decided to spam the map with shitty armies of zombies and wolves everywhere. Literally gave no shits when entire armies died. Won the game 50 turns later. I think the only high tier army I had running around was Kemmler's immortal stack. Back when there wasn't a regen cap. Impossible to kill anything in that army.
I've always kinda had an affinity to giant blobs of units rather than a bunch of elites. It was the same in Shogun 2 and FotS too. Having an army of like 2000 ashigaru was way WAY WAY scarier than like 500 elite marines.
I still treasure my screenshots of me winning battles 1v3 just by running at them until they all died.
My VH/VH vampire victory involved using Vlad with a bunch of zombies and skeletons for raise dead fodder, Isabella pretty much glued to him with an army featuring nothing but fliers and heroes (and even then, it was just like 10 units) and a solo vampire lord, also tagging along. Vampire goon squad can roll over pretty much everything.
I need to try out that subfaction sometime. Still haven't tried it yet, though I've been meaning too.
You can actually take West
and East Sylvannia by turn 6 or so with that faction. Yes, on VH/VH.
The way I did it: Start with Vlad. Recruit Isabella, and have the two heroes join her. Raise dead with Vlad, move over to the Moot, raise dead again, loot and occupy (so you don't get attrition, plus replenishment) the settlement. Next turn recruit a generic VC, move Isabella over to Vlad and have him give her all the bats and vargheists, before marching towards Drakenhof and raising dead again. Rush over both Isabella and the VC to Drakenhof (use forced march if you got to) in the next turn before besieging with Vlad and assaulting right away. You'll probably need to fight it out personally, but you can pull it off as long as you indulge in Lord sniping with your Lore of Death vampire and the vargheists.
Once Drakenhof is yours, you'll probably had enough casualties in the siege to raise more than a bunch of zombies and the odd skeleton. Next turn you rush down Mannfred with the Three Amigos and take Drakenhof. After that it's just mop up.
Vlad and Isabella get crazy strong when on the same battle. If you got Grim & Grave, you should also recruit whatever RORs you unlock in the process.
After this mad rush you can probably blitz through the Empire running on nothing but raise dead, or even just wipe out Reikland and go grab the Border Princes and Brettonia for your wincon. You can even do it before Archaon shows up, getting you an instant win.
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Currently doing a VH/VH Carcassone run, which is also my first real Brettonia run, and I've already managed to get 400 chivalry without leaving my starting province thanks to beastmen and low public order. I don't think CA anticipated this.