So this entire idea started when I was remembering that Mystic existed after they put out that UA with the Soulknife. The burning question I had in my head was "If the Mystic is the ultimate overpowered jack of all trades, could you solo a campaign with one?" I figured just one probably wouldn't be able to cover all of it, but maybe two or three could. So I went around trying to find 3 people who could be relatively consistent, even if one of them was a bit flakey. Now that I have players saying they can commit and a session 0 coming up, I realized I had no idea what campaign to run. I figured one of the official campaign modules would make sense, since WotC designed them and so shoudl be somewhat in line with the game balance they would design the UA around. I decided that as much as possible I would attempt to run them as is, with minimal changes unless forced by the players (Curse you for not following my railroading!) and I was wondering what would end up being a good test bed for this crazy idea. Note that I'm also basically just letting them do whatever they want by the RAW of the Mystic and there is a chance it becomes a ROFLstomp but that's ok. So what I want to know is what you guys think is a well designed adventure to run them through, and I'll probably post updates for how it goes so you can sort of compare them to whatever campaigns you may have played in whichever module ends up selected.

Run them through Tomb of Annihilation. If they can do that, then the class has passed all the tests. It's a pretty open sandbox until you are strong enough to do the end dungeon.

Run, just run. The most poignant piece of feedback I have about the Mystic ( the campaign I DM used to have one) is how freaking complicated it is. It’s not that OP, but watching players spend several minutes flipping back and forth through 30 pages to find something, giving up, finding it 20 minutes later, and you’re still in the same round of combat.... I wish you luck.