I know my experiences don't matter much to you random people, but I just felt the need to share this one. When I finally got to the great spyre, none of my friends would help me, and eventually I ended up teaming up with this myth archmage. But it turned out she was only farming the gurtoks, so once we beat them, I was on my own. I was just about to give up, but I decided what the heck, might as well try my hand at soloing Malistaire. I didn't expect to beat him, ecspecially since characters in the game tell you to bring friends, but I took out the minions with storm lord, stacked a bunch of blades and traps, and hit Malistaire with two consecutive enchanted Tritons. And that was enough to kill him! I'm so proud of myself right now
I'm a solo player (At least most of the time...). What I think of people who team up (In some worlds, the easy ones that I sped through anyways...) is that they can't defeat them without someone to do it for them. In some cases, that is true because their health is way too low for that world.
I do not remember where in Dragonspyre but I took down a boss with 9,000 health. Took me 30-45 minutes and I used most of my deck. It showed me I shouldn't freak out (The difference between Rank 5 bosses and Rank 6 bosses is big...).
Unfortunately, us Sorcerers don't share the same luck of having very powerful spells. I'm sure I can do Malistaire now as a 55th Level Sorcerer (I had to anyway in order to get the last stone rose even though I didn't need to), but not quite as easily as other schools with more potent attacks.