Credits to toegrinder for the covenant sims, they can be found here.
Night Fae Is a decent covenant in multiple target scenarios, the cooldown reduction provided by shifting power allows for more frequent burst windows and the damage from shifting power itself is strong. However, on single target it is very underwhelming when compared to kyrian, necrolord and venthyr.
In raid scenarios shortening arcane power cooldown accomplishes nothing unless you can reach a 1 minute arcane power cooldown, this is due to the fact that 1 minute cooldowns are very good for this tier (Inerva adds spawn every 1 minute, sludgefist pillars are roughly every minute, SLG adds etc.)
Therefore night Fae falls down and is actually currently the worst overall covenant for arcane.
The signature ability, Soulshape is absolutely insane, despite being a mage, I've got to use Soulshape so many times in raid testing as well as the maw/M+.
Necrolord is Arcanes overall best covenant. This covenant has some insane potential, due to the fact that you can essentially burst three targets at once, with amplified Arcane Blast damage. Whilst having that insane three-target cleave potential it is very strong on single target currently being roughly 0.9% behind venthyr. The spell damage increase alone from Deathborne is super strong even on pure single target and that's without even going into specifics about the Emeni soulbind which is currently the strongest.
Regarding soulbinds, Emeni has a very good trait called Lead by Example, and is currently also a strong option if you like Maldraxxus/Necrolords thematically.
The big downside of necrolord is the 3 minute cooldown, as it doesn’t line up with every Arcane power.
Kyrian had previously been misunderstood and thanks to mage theorycrafters the rotation for kyrian has changed and is now a very strong option on single target, being on par with necrolord and slighly behind venthyr similiar to necrolord. However on multiple targets kyrian is the second best covenant being beaten by necrolord.
Kyrian has a very unique playstyle. Unlike venthyr, nightfae and necrolord clearcasting doesnt matter a huge deal with kyrian, that is because your damage is centered around arcane barrage and arcane harmoy combination.
The general playstyle here is to gain at least 15 stacks of arcane harmony before burst windows, which is set up by using radiant spark with touch of the magi and Arcane power, then arcane blast 5 times followed by an arcane barrage. The kyrian playstyle is therefore way less RNG compared to the standard rotation which fishes for clearcasting procs in opener. Personally I find kyrian to be the most fun due to the low cooldown of radiant spark which allows for frequent burst windows.
Since patch 9.0.5 mirrors of torment provides a clearcasting proc on mirror comsumption, used to be 4% mana. It is currently the strongest single target covenant.
According to sims it is currently the best covenant for single target damage, however one thing I would like to point out with venthyr is the gimmicky interaction with mirrors of torment. For optimal usage the boss keeps casting and attacking and mirrors will proc every 6 seconds. However, there can be certain fights where this does not happen, for example on Sludgefist when he is stunned and takes increased damage, its a very ideal situation to have clearcasting procs ready, however since sludgefist is stunned he is not attacking and therefore not proccing mirrors of torment. This can be played around, with using it before to bank up stacks.
Even on non-extreme situations which Sludgefist is, there can be times where the boss starts channeling and channels do not count towards mirrors of torments, like hungering destroyer or sun king shield etc.
On multiple targets is it decent being only better than nightfae.
Soulbinds and Conduits
Standard build (Arcane echo)
Magi's Brand - Assuming you have the mythic 0 conduit, you gain an additive 7.8% accumulated damage. Yes, additives make this conduit insane.
Necolords and Venthyr arcane mages will play Arcane Prodigy alongside Magi’s brand to make Arcane power a 1.5minute cooldown, which lines arcane power up perfectly with Deathborn (Necrolords) or Mirrors of torment (Venthyr)
Kyrian build (Resonance)
The kyrian specific conduit is your best in slot, however if you are kyrian you will play 2 potency conduits regardless which will be ire of the ascended and Magi’s brand, see the soulbind tree below.
Kyrian build (Resonance)
Nothing changes on AoE, you will play the same conduits and soulbind on AoE as on single target.
Same as the single target build
Arcane Harmony - Best for kyrian on single target.
Temporal Warp - Best for non-kyrians on single target, however if you don't use bloodlust on pull harmony will be better.
Arcane Bombardment - AoE, that's it, nothing compares on AoE even for kyrians.
The two recommended trinkets are:
- Sinful Aspirant's Badge of Ferocity which is from PvP
- Empyreal ordnance which is from the dungeon “Spires of Ascension”
These are two on-use trinkets, so what you want to do is use your Empyreal ordnance on pull, then start casting to fish for clearcasting stacks, 20 seconds in you can use the badge trinket and all of your cooldowns. You will have two intellect trinket buffs during your burst, and this is super strong with the necrolord and your best trinket setup for that covenant. If you are venthyr you can swap Ordnance to a cabalist Hymnal or another passive trinket if you dont like two on-use trinkets.
- Cabalist's Hymnal which drops from Sire Denthatrius (the end boss of Castle Nathria)
- Soulleting Ruby which drops from the dungeon “Theater of Pain”
Since kyrian does not use any cooldown reduction conduit/effects arcane power will be a static two minute cooldown always, and soulleting ruby lines up perfectly with that. It is currently almost 1% better than the 2nd option which is Dreadfire vessel from mythic sire denathrius.