I've taken the SMM with the Changeling. In fact, that's what convinced me it was a balanced class
Oh, I'm sure you can
defeat him with the right setup, but why would you want
to? He's going to consume way more resources than any other boss.
Anyways, if you consider Transmuter and Vampire "balanced" on the stronger side of the class spectrum, then I'm sure
the Changeling qualifies as "balanced" on the weaker side of the spectrum. I have gotten some good combos out of him, but he's neither reliable nor particularly hard-hitting compared with the game's stronger classes. I'd probably put him in the same category as the Crusader in that regard.
There's a trick to using monsters as a resource that I think a lot of players aren't seeing right now. Hint: Low level monsters aren't it.
Not really much of a hint, but I'll think on it.
Assassin - I used a Goblin for this one.
Same here; it's really easy to get stuck a few XP short of a levelup on Boss Hive so the goblin makes A LOT of sense. Relative to the rest of the level the boss is easy, so considerably less of your prep-work goes into his takedown compared with ranked mode. I got Gharbad on my assassin run, so I had to level up twice while fireballing him with my mana until I could first strike him down.
Also, while I didn't like the old Goblin glyph conversion for "real" runs, without it, it is so annoying to get max gold before starting your runs in this version.
Just copy your save file to a backup directory, then restore it whenever you "fail" a run to revert your gold amount. For most of us here, there's no longer anything to unlock after the Changeling anyways.