what build do you want??? dps, tank, healer???

Did you really post asking everyone here to create your entire build for you?

ok, now if you choose magika build you can play any role you like. You need to open 1h&sh, desrto and resto weapon skill lines and light and heavy armour skill lines.
for AoE DPS Sap essence+elemental ring+ elemental blokade+twisting path
for single target dps elemental drain+crushing shock+imaple+crippling grasp
for heal resto+siphoning
for crowd tank - 5heavy armour shielded assault + defensive posture morph + sap essennce spam with leaching attacks on (shields from undaunted or armour\spell bonuses from armour or guild skilllines on your taste)
for single tank - insread of sap essence - funnel health + inner beast + impale (for finishing).

With 1.6 coming I believe stamina nightblade dps will be more viable than magicka nightblade dps, if it isn't already. You can go dw/dw and with pretty much by doing a spam of rapid strikes and not even thinking you can push around 800 dps, and played right above 1k and if played very well around 2k.
Single Target- Incapacitate up, rapid strikes while animation cancelling heavies, apply rending slashes as neccesary for DoT.
Multi- Sap/Power Extraction (I switch to power extract for trials as you receive more damage and you are receiving enough healing to not need sap, and sap for DSA and Vet Dungeons) then spam steel tornado
Use rest of skills to support the above combinations
Depending on what you can get access to, gear some combination of the vicious ophidian set, hunding's rage, ashen grip, and shadow walker.

Magnus gift or Seducer (5). Torug pact (3) or Twilight embrase (4). Warlock jewellry (or PvP vendor rings with spellpower bonus for pair).
Martial knowlege (5) + seducer/magnus (3) for dps.
Other combinationt to rise spellpower and magika regen as after 1.6 all magika skill will scale of spell dmg.