my main character was a vampire when i first started tanking with her, it was alright but i really would not take a vampire tank into every veteran dungeon

and definitely not stage 4, health recovery is pretty important for tanks

Only time it is ever useful is if you're hurt.

This means the passive is only effective if you're taking oppressive sustained damage or deliberately staying at low HP to take advantage of the massive damage bonuses on the spammable and it's morphs.

Tanks in PvE rarely sustain oppressive sustained damage as ZOS enjoys and loves it's 1 shot mechanics. That said, it doesn't mean they don't exist... You just have to know what kinds of damage you're taking, and prepare for that encounter accordingly. If you have don't know and wanna be flexible I recommend having an Armory assistant with a non-vampire tanking build available, or a lot of Purifying Bloody Maras and Corrupting Bloody Maras.

Vampires are more trouble than they're worth as PVE tanks. It was popular for a while —— for the extra ult —— but it's hardly used anymore. The vampire's damage reduction passive is powerful in PVP because most damage in PVP is minor and you have plenty of buffer to make the passive work. But in PVE tanks face a lot of one hits that can be as high as 100k (some of which is also flame damage). You'll probably die from the punishing effects of Vampire before you get the benefits of the Vampire passive

technically speaking, you will never hit 30% dmg reduction from that passive, you get that at 0% hp

since its a scaling DR, you would already have to be dangerously low hp for it to even trigger, and generally, say for vet trial situations, if your under 50% hp, you are already in danger of being 1 shotted if your the main tank, which at that point the dmg reduction wont even apply fully

as others mentioned, some of the skills were used for utility (mist form pre-nerf or the drain for ult gen), i see the drain working better on an off tank that is not constantly tanking things (such as during kynes aegis, where an off tank is almost not needed except in a few fights for a brief time)

so my opinion is if your going to be a vamp, you likely dont want higher than stage 1, since hp regen actually makes a difference in pve

Necro off tank at vamp stage 1 with vampiric drain. Alternate this with necrotic potency and saxheel champion it's an ult generating monster that buffs group DPS a lot.

I dont see any real use for vamp outside of this for pve at least.