I tried Frost and Arcane for Jin'rokh 25 HC, but all the "clever" strategies I tried never got me much further than 50%.
And then I turned my brain off, and remembered that I am an Arcane mage, and that current Arcane spec is nothing but a cooldown stacking, RNG relying, 100% proc dependant monster.
A few pulls to get the right procs and boom, gimme some 932k Arcane Blast crits and 230k Leech ticks baby :
Jin'rokh 25 Heroic
And as much as I hate PC and the current Arcane meta (Prophecy of Fear, I hate you), I am sure that at some point during Legion, I am going to miss this.
On a not-so-unrelated note, I got a few pulls of Kargath NM and got him to 40% using the same Arcane nuke strategy. I do not deem him impossible yet, but the damage output is crazy and the survival is limited. I tried Fire with a full Leech build but it doesn't work at all.
Also isaac, awesome job at Twins 25 and please kill Paragons, I hate this boss SoO much
Finally, bowchikabow suggested a few pages ago that we could do a "speedrun leaderboard" for Mage soloing. I am not personally a fan of this idea for several reasons, so I will not handle this task should it become reality. My reasoning is that WoW is not a good speerunning game, because there are too much parameters to take into account (gear being the top one), much like regular soloing where luck plays a huge part too.
Also, pre-MoP content would be completely uninteresting to record, because every boss gets oneshotted (0.28s kill, new record ! Record was 0.30s), so that leaves us with just 3 raids to work with, with many bosses still on the hard side (end SoO especially).
So, should the project be concretized, I would be happy to see the result and maybe compete, but because of these reasons I won't assume this task myself.