Ruin Explorer
Legend
I love all this except prestige classes being tied to diegetic achievements, which I want to love, but it is really, really tingling my Spidey-Sense. That's because unless you also have instructions/fairly strong suggestions for the DM to try to cooperate*, that's just going to lead to weird and unfortunate situations where some PCs are given easy access to powerful PrCs (there's no way they're perfectly balanced, some will have insane synergy with certain classes/MC combos, but be totally useless to others) that suit their class(es) perfectly, but others will just... not. And if you absolutely have to use a PrC to advance 7-14 (like, you literally can't use a base class), then relying on diegetic achievements is particularly bad, because they've got to have happened already in levels 1-6 (which isn't a lot of sessions in most versions of D&D!), or some players may end up having to pick really dire-for-them PrCs for their PCs (not just mechanically, likely also thematically/RP-wise). The same applies to master classes fully.My ideal would be something like this, although I'm not tied to any of the specific details.
1) At character start, there are something like 20 classes, all of which go to level 6. Every character picks 2 of the 20, although there are special rules for characters who want to pick just one.
2) Characters pick a prestige class at level 7, which covers advancement from 7 to 14. There are a few prestige classes in the PHB, but most are in the DMG or later supplements, and are tied to diegetic achievements, not character build.
3) Characters pick a master class at level 15, which advances to 20. Just like prestige classes in that almost all of them are discoverable rewards, not build tools.
No level-by-level multiclassing.
What would you propose to avoid this issue