I was looking at Arcane and I saw that they can do pretty insane CD stacking in legion.
Erosion - +20% damage taken from Arcane spells on target for 10 sec. 1 min cd. Rune of Power - +50% damage for 10 sec. 45 sec recharge. Incanter's Flow is still an option of RoP is too inconvenient. Arcane Power +20% damage (can be +30% with Concentrated Power at the cost of PoM). 1.5 min cd Static - Grants 4 instant Arcane Blasts. 1 min cd.
Get 4 stacks -> RoP/5 stack Incanters -> Erosion+AP+Static -> Spam 4 blasts into Supernova into Arcane Barrage. Minimal to no casting. This can be repeated every 1.5 mins.
I like this design for arcane though, arcane SHOULD be scary if left alone/every 1.5-3min with CD's, made up for with being way squisiher than frost (arguably not the case anymore due to every spec having two blocks, cold snap, etc etc)