This is how I've been kicking some major butt in solo play recently. I'd say it's an absolutely amazing mob-grind build, but I've been having fun in dungeons, too.
I can't speak for its effectiveness in endgame content, but this is a build I've been using past week or so and I've managed to solo just about everything with it, with little effort. Including group dungeons. That should speak for its effectiveness while leveling. I'm running with full light armor currently. I'm not sure if 5 light, 1 medium and 1 heavy will be better, I don't have the undaunted perk yet. Note: I'm no theory crafter. This build developed during a bit of curiosity as to how effective it would be. I was pleasantly surprised.
I'm wearing 5 pieces of Torug's pact. I upgrade the gear about once every 10 levels, having a clothier is really useful here. I'm also using Orzorga's Red Frothgar food (increased max health as well as increased magicka regeneration). As of now I don't really use any potions, but I reckon any spellpower/magicka restore would do very well. I have yet to struggle with my resources, due to siphoning strikes and the assassination passive which is up pretty much all the time when fighting groups of monsters, due to its execute.
Main hand, dual wielding swords, is my source of damage. I always keep up Refreshing Path, which is a tremendous help both in solo play and with a small group. While Twisting Path would deal more damage, this morph makes life considerably easier for healers while doing dungeons and it keeps you alive through virtually anything during solo play. I also make sure to keep up the damage buff from Sap Essence at all times. My main damaging ability during single target damage is Swallow Soul, which is easy to weave with weapon attacks. My gap closer is Lotus Fan. I'm considering to un-morph it due to its stun, but either way it works quite well here. AoE damage is provided with Sap Essence spam, along with Refreshing Path. I use my ultimate, Soul Tether, whenever available, except during boss fights with occasional add spawns, in which case I place it over those adds.
Offhand is my buffstick, a few "Oh crap" buttons and an Ultimate that deals more damage, but sacrifices group and solo survivability.
As for race, anything magicka focused should do. I guess Altmer would be the best option, but I'm doing just fine as a Breton.
Edited by SerpentbreeD on May 10, 2016 3:55AM The path to enlightenment is paved with the corpses of the mindless.