Did OP read our posts in that worst skill combo and take it to heart? Some of us said stamina vamp in there
WW = Stamina
Vamp = Magicka
This is the way the world works OP
I can be wrong but I totally disagree with you guys.
Beeing stamina build does not mean you can not use one or two magic abilities. Drain essence is not so good skill, but templars have no escape skill and having a mist form as a only magic ability with purifying is viable.
Bat swarm damage scales from highest damage so it does not matter are you stam or magic build.Vampire passives are good.
Still the vampire dies much more easily than the normal person. Fire kills you fast and so does fighters guild abilities. You can try vampirism and if you don't like it you can cure it.
So vampire-skill line is best for magic builds but works also with stamina. Still you must know that werewolf is usually still way more better cause all damage is physical and it comes with many good passives. But i recommend to try both and then decide.