First of all, There is no legendaries involved in the following rotation and I'm gonna use the build which I assume might be standard in NH Raid environment 2223131:
Amplification, Slipstream, Rune of Power, Resonance/Charged Up, Chrono shift, Erosion (or Unstable Magic), Overpowered
Update (23/01): I step away from Charged up for the moment and prefer Resonance. Nighthold has a lot of adds fights and even in single target I find Resonance to perform better for myself. However I think Charged up shines with The mystic Kilt.
But what I really want to talk about it the rotation. Here is what I came up with
Rotation 1.0 (01/09)
So what's going on here ?
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1) Maximizing Arcane missiles Potential with Rune of Power
Arcanosaur, an Arcane mage from the US forum, got my attention with a talk about maximizing arcane missiles potential. Basically before, I used to mindlessly dump my spells regardless of the number of Arcane missiles charges I had in bank. But now with the talent Amplification, our missiles are much more valuable. I found out that "only" casting those during Rune of Power (wait for ToTm Proc?) yield awesome results. I now bank my missile for my next Rop and it feels quite nice. I also now use Arcane barrage -> Charged up Combo during my 3rd Rune of power for even increased dps
2) 1 minute cooldowns
Presence of mind and Mark of Aluneth are two important spells that don't align naturally with our burst windows. We can simplify this problematic by simply delaying those spells to hit with Arcane power and not worry about it. But in the long run we might simply lose casts of those two spells and lose a huge dps potential. This happens on a ~4:15min fight for example: Time for 4 Mark of Aluneth & Presence of Mind, but time only for 2 Arcane power.
In my opinion, in those cases we should use Mark of Aluneth on cooldown, keep Presence of mind aligned with arcane power, but during the last moments of the encounter, use Presence of mind early cooldown to finish our burst.
3) Legendaries & Set
2Pc Set Bonus &/or Rhonin's Bracers: You probably won't need to enter a mini-conserve phase after your second burn, since the procs will give you enough free spell to stall for that Evocation Cooldown. note: Rhonin's Bracers has received both direct (down to 18% proc chance) and indirect nerf, since we don't use Supernova and Nether tempest. With the 2pc this legendary item might become better
4Pc Set Bonus: I think we can debate a lot about this one. It's a tricky situation, my only assumption is that it will be good with the Legendary Hat Gravity Spiral. If you don't have it however, the cooldown reduction will never put evocation available before Arcane power, so I can't see much use to it atm.
Shard: Just use the 2nd timewarp during the 2nd Arcane power
Kilt: You're gonna be able to extend your burn phase by a lot with the Arcane barrage-Charged up Combo. During Conserve phase you can keep burning to 15-25% mana before using Arcane barrage
New Gravity Spiral hat: You gain an extra burn phase right after the first one. This might become even crazier with the 4 pc set bonus, resulting in a "never ending burn phase" meaning you will never have to cast arcane blast at 1, 2 or 3 arcane charges nor cast arcane barrage to clear in order to regen mana. There is a good amount of theory crafting material with this one.