The thing i speak here is the most broken mechanic as of now in-game. I'm long VR10 player, and most of my guildmates are also VR10 or high VR players. I'm not here to cry about something that i don't understand etc. We are sick that after almost 3 weeks since release Zenimax don't do anything against that. One of the popular PTS testers even show you that bug BEFORE release
https://www.youtube.com/watch?v=SmKEzoikMq0 . It won't work for most of the vampires. In our guild we have 5 vamps and only one have ability to abuse that bug/exploit. Basically your ultimate cost on stage 4 of vampirism cost 40 ultimate. Yes, 40 ultimate for constant ~200 dmg per second with ridicoulus heal. It last 5 sec, in zerg you can use just this ability for damage because you get that ultimate before previous one expires. The better thing is it works even if you use Elusive Mist 0,5 sec later and while you are in Elusive Mist you still get the heal! So right now 2/3 of the top leaderboards on most campaign (atleast EU Dawnbreaker, Skull Crusher and Scourge have that kind of groups) are ppl/groups which abusing this exploit to the point that they can kill zerg 3v30-40 ppl, because the more ppl enemy have the more they are healed, and you can't do anything against -75% dmg reduction and few thousand heal per second in the same time. On Dawnbreaker, players (actually most of them are one group) that abuse that 24/7:
Cherooke (TOP1 player, 500k+ AP in last 2 days)
Takhisi
Rhaw
Dex
Takeru Uchiha
Zero
There are probably more but i don't want to place nicknames that i am not 100% sure or i don't remember.
Right now pvp players have 2 options, get vampirism and hope for the bug working for you cuz Zenimax don't give a **** about that for weeks and prob they don't do anything for few more or don't play in any group pvp because there is no point to do that, you can easily killed them 1v1 or 2v2 but you can't 2v10.
There are unbalanced abilities on pvp like unlimited teleport for Sorcerers or ridicoulus dmg from Molten Whip (600-700 without crit) or more and more popular Bash builds but this one isn't unbalanced or overpowered it's just broken to the point that most of my guildmates are considering quit if they don't fix that till 1.1 may content update (Craglorn).
Sorry for my bad english, it's not my native language.