I really like your class ideas. I mean, why not? That said, would the game map to those wild classes? Feels like Lost Mines of Phandelver isn't "wild" enough to match the classes. So I'd love GM advice on how to "wild-up" my game...Man, it's been a while since I touched this idea, and now I've got a wild idea to just bundle all my 'fantasy RPG heartbreaker' ideas into one book: a megadungeon with showcase dungeon adventures, using 5e rules but with a suite of custom classes designed specifically for the campaign.
Like, screw 'fighter.' No, you're a 'fusilier' with mastery of mount and musket. Forget 'cleric.' You're a 'penitent,' deriving divine power from a great sin you are seek to redeem yourself for. No time for a 'wizard.' You're a 'rhabdomancer,' crafting wands from magic items you destroy and from the remains of creatures you kill. There are no 'rogues' here: you are a 'leper,' diseased and deadly.
Or I could be goofy, and make classes like 'mushroom man' and 'roofer.' What does a 20th level 'roofer' look like? I dunno. He probably throws very lethal shingles.
Like, design monsters specifically to do cool things in relationship to PC abilities, and design PC abilities to combo, and to unlock certain tricks as you level up to make the Metroidvania gating possible. Rather than being a supplement to an existing game -- like a new episode of the TV series we watch each week -- make it more like a special event mini-series prestige HBO thing.
One thing Freebooters on the Frontier (pbta) does for XP is grant xp individually if the PC does a Class goal and an Alignment goal every session. Then everyone gets XP if their party "Finds some cool loot"; "Fights something major"; and "Figures out something about the world" (not those words). There are a couple other ways to get XP also, although not as much as Dungeon World. Also, there's another advancement economy - when doing moves that relate to an attribute (the classic 6 - STR, DEX, CON, etc) if you fail, you mark the attribute. 5 marks, and the attribute goes up by 1 (from 10 to 11 for example).