These, along with other undead types, were spotted in many zones and varied greatly in level. They surfaced after The Buried Sea was released and disapppeared on servers after the "Two Gods" event was defeated in Solteris or after Secrets of Faydwer went live, whichever came first.
Just spotted a lvl 32 one of these in The Overthere on the Mischief server today (Dec 19, 2022). I was exiting the outpost to run to the PoK zone, and saw something in the distance slowly walking towards the outpost that looked like a humanoid, but not a Sarnak. Targeted it, and was like ????. Killed it and it dropped a Symbol of Mistmoore.
These Guys suck really they show up unexpected an unwanted an try killing ya not cool. Had run ins in the ascent working teair 2 don tasks with DB's an again in SF working my clerics epic with LB's. Though they not to hard ta kill they are still a pain for 75 lvl war specialy when your already dealing with multiple mobs.
Also found in skyfire. Dark blue con to a 65 and hit hard. I also seen them in Mnts and were totally different. One in SF dropped a coin. Looks like they are related to dusty mummies and agitated skeletons too. Keep seeing them where these vampires are, and they are everywhere.
I ran into one of these last night while farming plat from the HG's. Went down pretty quick and dropped a vampire claw that sold at a vendor for a little over 60pp