I'm still absorbing all the material from LU (it's really A LOT!), so I cannot comment on things like balance or adherence to LU monster creation rules.
That said, this example shows how much deeper and versatile PNGs and monsters can be, especially iconic ones such as Strahd von Zarovich!
The collection of abilities, skills, spells, maneuvers and vampire traits is really staggering and frightening to behold, definitely the ultimate villain of a campaign in Ravenloft.
Given its complexity (a 3 page stat block is surely not easy to run properly), I'd suggest to try the following
- group all effects/traits/skills/maneuvers by type of usage: actions, bonus actions, reactions, non-actions, etc
- include the description of most usable spells in combat, and put them in the appropriate action type list as above (this is consistent with the little I've seen for LU's monster stat block design)
Additionally, I'd consider the following
- legendary resistance is 3/day but without any loss on Strahd's side. I recall that in LU when monsters use legendary resistance they show signs of getting weaker, both in a purely descriptive sense but sometimes also from a mechanical pov (lowered AC, etc). Maybe you could try to incorporate something like that, for additional flavor
- a good deal of the "build" revolves around him riding a mount, which is very cool. At this point I'd really love having a related stat block for Buchephalus, with the LU treatment
- I'm still not versed in LU monster design rules, but I'm not sure you can use multiattack with combat maneuvers that require to use an action and allow to make multiple attacks using the Extra Attack feature (the two are not the same)