I appreciate the tips. But to be perfectly honest, I’m just gonna wait til 70 to continue farming legion xmog/mounts. Hopefully, we’ll be able to literally 1 shot legion stuff then.
With how old it is(5+ years) and being 2 xpacs old, you’d think we’d already be able to go in do that, but no. Blizz thinks you need at the very least zereth mortis gear to solo legion mythic. 
I mean I’m not killing it in 1 GCD, but 1 to 3 mins a boss on Mythic (with exception to a few like Immonar, Sargeras, Fallen Avetar and Eonar), On heroic and lower I’m pretty much killing them within 30 seconds.
EN and Nighthold Mythic your basically killing all bosses within 30 seconds with exception to Gul’dan and Ellisande with their immune phases and Xavius with his add phase.
So in a nutshell only ToS and Antorus do the boss fights take 1-3 mins on Mythic. Which is worth it so you can get the raid skip quests done.
all mythic legion is soloable except for kil jaeden
you need to be a specific class for it. i wont name names
Yes and No. Really you need a class/spec that has self healing or barriers. Warriors are screwed except for Arms if you have second wind I belive will work. Mages (especially fire with blazing soul) can solo him especially if you have the conduit that heals you as your barriers take damage.
But right now he is soloable by most classes.
I did it as frost without that conduit, tempest barrier+ ice barrier was more than enough for I1.
It’s also in Legion, where the heart of azeroth still works, so you can use crucible of flame to heal yourself if needed.