I'm actually getting some Slay the Spire vibes from the key mechanic for the final boss. Spending resource to get a key in Book 1, and taking a burning elite in Book 2 in order to unlock the final boss. Kinda dig it, really.
Honestly I feel pretty good playing on Rank 10 for decent enough balance between fun and challenge. Understand your recommendation to stick at 0 or 1 but honestly the modifiers keep villains and enemies interesting
I laughed at "I know about 50% of what's going on with this game's lore." I was like, wow, that's about 10x as much as me! This game has, by far, the most nonsensical and schizophrenic lore of any game I think I've ever played...
I think Mimic with the Magma Miner challenge modifier is ridiculously difficult, yes. If you roll Weaver/Mosscloak in any order I think it's a lot more manageable.