I'm a level 18k elf and I "only" used 35 stones. The black moon followers were a non-issue, aside from confusing the player at the start of the fight and making it seem like it was about the portals instead of the dragon. I've been soloing and avoiding aggro for as long as this game's been around, and these guys won't bother you as long as you leave them to the NPCs or give them wide berth.
The boss strikes me as one of those MMO bosses that are intended to be ridiculously hard if you don't have a group with you, but thankfully not impossible. He concentrates his aggro on a single person letting others pew pew pew from a distance. If you go solo, he's only got one place to concentrate his aggro...you. And he will run over you constantly over and over again.
My experience is I was doing decent damage to him despite the aggro as long as I had ladeca up. Once it went down (and I had him about 3/4 dead at that point), I spent a good 20 minutes getting run over before being able to damage him at a decent rate again. (Final shot is good, but doesn't last very long in comparison and was hard to keep up while getting run over.) Then Ladeca and Exploit Weakness came back up and he went down pretty quick. I think some of those extreme endgame players probably could have soloed him before the skills in question went down, using less ladeca stones, but that's just my guess.
That said...the random petrification made this boss's tactics kinda...cheap? I imagine Nexon just figured that most players have a stash of stones from various events. (Which they'd be right, but it was still pretty annoying...)
I'm actually kinda grateful that the fight did *not* require a group as long as you were properly geared/supplied. Groups in MMOs in most situations annoy me, because it feels like you're always trying to dodge gear snobs and other elitist jerks when all I want to do is enjoy the story and chat with others while I do it.
I think the issues are occurring because they're trying to get this set up.