ALL Credit goes to Rueben "Jabba The Hutt" Vann

Rotation: Use the Back Bar (Bar 2) to apply your buffs every 20 seconds - Power Surge, Boundless Storm, and Dark Conversion. Once buffs are up swap to Front Bar (Bar 1) and gather your adds. Once you have all of your adds gathered lay down your Liquid Lightning, Elemental Blockade, Pulsar, then two heavy attack. Use Ultimates and Hardened Ward as needed. Rinse and repeat.

Videos of his build:
Video 1

Video 2

Video 3

Video 4

Main Hand - Thunderbug's Lightning Staff - Spell Damage - Sharpened
Main Hand backup - Thunderbug's Lightning Staff - Spell Damage - Sharpened

Head - Netch's Touch - Max Magicka - Infused - Light Armor
Chest - Thunderbug's - Max Magicka - Divines - Heavy Armor
Shoulders - Iceheart set - Max Magicka - Divines - Medium Armor
Waist - Netch's Touch - Max Magicka - Divines - Light Armor
Hands - Netch's Touch - Max Magicka - Divines - Light Armor
Legs - Netch's Touch - Max Magicka - Divines - Light Armor
Feet - Netch's Touch - Max Magicka - Divines - Light Armor

Neck - Thunderbug's - Spell Damage - Healthy
Ring 1 - Thunderbug's - Spell Damage - Healthy
Ring 2 - Thunderbug's - Spell Damage - Healthy

5 Netch, 4 Aether, 2 Valkyn Skoria, for group dungeons
4 Person group or trials is 5 Netch, 5 Aether, 1 Kena or Iceheart
4 Person group when someone else is wearing 5 piece Aether, or soloing normal dungeons - 5 piece Netch, 4 piece Burning Spell Weave or equivalent , 2 piece Valkyn Skoria

For a Pet build - Better single target DPS, worse AoE damage

On Bar 1 (Front Bar) - Use Summon Volatile Fimiliar instead of Pulsar and Elemental Rage instead of Eye of the Storm ultimate

On Bar 2 (Back Bar) - Use Summon Volatile Fimiliar instead of Pulsar and Summon Charged Atronach instead of Energy Overload ultimate

Rotation - Make sure your pet is out - Then buff yourself using the Back Bar: Power Surge, Dark Conversion, Boundless Storm
Swap to Front Bar and cast Liquid Lightning, Elemental Blockade, Pet Buff (Same button you use to summon your pet) then two heavy attacks and then re-apply Liquid Lightning, Elemental Blockade, Pet Buff, and two more heavy attacks, re-apply Liquid Lightning, Elemental Blockade, Pet Buff once more, swap to back bar and rebuff. Use Hardened Ward as needed, Ultimate as needed. Rinse and repeat.