I Solo'ed on my Pally on Tuesday. You have to kill the tainted (Green) water elemental's, I think she was at 62 stacks when the last one finally spawned.
Kinda annoying that I cant do this boss on my green geared alts she just completely wrecks me before I can kill her
I had a lot of trouble doing it on my decently geared WW monk, but as MW or BrM it was easy. Hunter and warlock with tanking pets were trivial. DK and Paladin were trivial in tank specs (and my DK is geared anyway). Warrior can do it as DPS with second wind no problem, warriors never die. Didn't try my undergeared rogue, mage, shaman, or druid (but I bet I could do it np as bear). Rogue and mage would be rough, and shaman would be challenging too.
I did last week on my lock and priest, and I think that Blizzard nerfed how quickly the tainted elementals despawn.
It felt much easier than I remembered it in cata where I absolutely had to use nitro boosts or else they would despawn before I could tag them.
Solo'd yesterday on my mage. Annoying fight. You just have to move quickly and get tainted, rinse and repeat.
Diablo: RoS; 70 Wizard.
I tried soloing on my priest, but ended up perma-feared by the strider. I gave up. I'm sure it's super easy with a pet...
The strider doesn't continuously cast fear any more, but there's only a ~4s pause between fears. You need to get an instant-cast on him (SW:P). He has hilariously low health so a DoT tick or two will kill him. The SW:P DD component may be enough, actually.
Also, prioritize striders, get those buggers down. They're crazy annoying.