While there's no min-max reasons to play a Magicka based Arcanist over the Stamina version - even in 4 man or solo content considering all your Penetration passives allow you to play with 6 Medium Armor pieces - if you want to play a Magicka Arcanist, it's totally doable and still really strong.
Recommended race: Altmer (High Elf) or Dunmer (Dark Elf); for solo or 4-man content Khajiit will have an advantage.
Recommended potion will be Essence of Heroism.
Recommended food will be a green Max Magicka food such as Firsthold Fruit and Cheese Plate.
Recommended Mundus will be The Thief (for group content like Trials).
For trash fights, you can essentially use the Stamina Arcanist's setup and instead of Stamina glyphs on the armor pieces, it will just be Magicka glyphs.
The Pragmatic Fatecarver compared to the Exhaustive Fatecarver is actually not that much of a DPS loss. Even if you do lose 3 beam ticks (4.5 seconds vs 5.5 seconds), the beam being a channeled skill means that you can cast a skill earlier after 4.5 seconds compared to 5.5 seconds, allowing you to compensate those 3 beam ticks a bit (Cephaliarch's Flail damage is about 2.15x of a beam tick tooltip-wise for example). So while it's still a DPS loss, it's not that huge as you 100% take the tradeoff in actual content.
The class will definitely shine a lot in raid environnement, thanks to the Pragmatic Fatecarver's shield making you pretty much immortal (you can even use the Bastion Fitness slottable).
On paper, the skill priority with a somewhat dynamic rotation is as follows:
I would really recommend sticking with Xxploiter, it's exceptionally strong on the Arcanist where so much of your DPS is backloaded in your Ultimate timings.
Introduction
While there's no min-max reasons to play a Magicka based Arcanist over the Stamina version - even in 4 man or solo content considering all your Penetration passives allow you to play with 6 Medium Armor pieces - if you want to play a Magicka Arcanist, it's totally doable and still really strong.
Recommended race: Altmer (High Elf) or Dunmer (Dark Elf); for solo or 4-man content Khajiit will have an advantage.
Recommended potion will be Essence of Heroism.
Recommended food will be a green Max Magicka food such as Firsthold Fruit and Cheese Plate.
Recommended Mundus will be The Thief (for group content like Trials).