This build is very squishy, under no circumstances should you start long fights. The build is made to instant kill enemies and vanish.
Attack from stealth with Onslaught ultimate, light attack and Caluurion's Legacy will also proc for insane damage. Always prebuff with Race Against Time. Vanish with Shadowy Disguise.
Skills Explanation
Shadow Image: Can be used to teleport back to safety, you can also use another skill here if you want.
Race Against Time: Speedbuff Major Expedition and Minor Force, increasing damage. You can also use other morph Channeled Acceleration.
Surprise Attack: Your spammable, deals great instant damage.
Shadowy Disguise: After attack this can be used to turn invisible to get away
Resolving Vigor: Your heal
Onslaught: Your Ultimate, make sure to have it ready to gank someone, deals insane damage.
Sets Explanation
Oakensoul Ring: Applies a ton of important buffs that boost our overall damage, survivability and ulti regen. With this item you don't even have to prebuff anymore because you already have all the juicy buffs.
Caluurion's Legacy: Powerful proc set that deals insane direct damage. Always procs when we pull off our gank combo.
New Moon Acolyte: Lots of extra Weapon Damage. You could use another set here if you want like Spriggan's Thorns if you don't want the extra cost on your abilities.
Kjalnar's Nightmare: We use 1 piece of this to get some more weapon damage. You can also use another one piece monster set here if you want.
Why Vampire?
Stage 2 Vampire is needed because we can use stealth without movement penalty due to Dark Stalker passive. Also Strike from the Shadows gives us extra Weapon Damage.
Outfit
Spiderkith Skin https://eso-hub.com/en/collectibles/spiderkith
Annihilarch's Chosen Greatsword
All Void Pitch dye, sword has a mix between Void Pitch and Scintillating Scarlet