Introduction
Liko with the help of Bread and Milk goes over Magicka Necromancer PvE DPS'ing in the video below. Make sure to support Liko at his Patreon! And check out his website, Liko.gg, a friend of the ESO University website!
Rotation
The video above showcases a more DOT-focused Magicka Necromancer rotation. The premise here is that if you cast enough Blastbones, then in-between you should have enough time to cast all of your DOTs. Cast Blastbones 1-in-3 skills whenever possible. Keep up Mystic Orb, Skeletal Archer, Scalding Rune, Degeneration and Shock Siphon inbetween.
Also do keep up Unstable Wall, but due to it's reasonably high direct damage portion, feel free to recast this early if there is nothing else that needs casting. Recasting Scalding Rune early works too!
Replace one of these DOTs (or Inner Light) for a spammable such as Skull or Force Pulse if you feel like you need one, which in certain fights would be beneficial.
My first choice would probably be Degeneration. Wherever you feel that you will less frequently get the full value out of DOT casts, I would go with a spammable. In execute, you can keep this rotation up, since the passive crit chance bonus will do the heavy lifting for you!
Static Rotation
Adapted from, and seen in Sparrow's Video above.
Start: Arcanist - Trap
Repeat:
BB - Degen - Unstable - Boneyard
BB - Orb - Scalding - Siphon
BB - Spam - Spam
BB - Degen - Unstable - Boneyard
BB - Orb - Arcanist
BB - Trap - Siphon - Spam
Parses