It still sounds like a really lot of charms... and some might be not so easy to use, because, for instence, events might happen when you don't expect it, and so you might have no idea taking out your goblin invasion, or pirate invasion charm, before they actually arrive and after it, you're probably rather busy with them...I agree that having so many normal charms could lead to your inventory just being clutered with them but that's why I also suggested the idea of fused charms to lessen the issue but a diffrent way to do this would be to just have 1 universal charm that you "charge" with the banners without making ones for each enemy but I feel like that could make it too good. Also I doubt that you would carry that many charms at the same time, you would just think about what you're going to do and take the charms that would help. For example I wouldn't take any jungle related charms if I'm fighting the Goblin Army. Also about the number of charms, there are 248 enemies (+ 4 critters, 5 from Old One's Army and 43 rare enemies [based on Lifeform analyzer] but I didn't count them) and I would seprate them into 52 fused charms based on bioms + hardmode version and events.
As for the Geomancer idea I really like it, it sounds interesting but would be really hard to fit into the mod unless you would rebrand the mod to something else, also maybe instead of calling it Geomancer it could be something like Elementalist since Geo just makes me think of rocks.
the general idea is interesting though.
As for the geomancer, the name idea is from Final Fantasy, Grimoire to the Rift, I think, there that's one of the possible classes of Gria. and they also use batons as main weapons, and spells that are based on the weather, biome, and the ground they're standing on, I think.
That's largely where the idea comes from too. because if you think about classes there, there are lots of classes. But almost all can be placed within the "melee-ranger-mage-summoner-bard-cleric/healer-thrower" classes. e.g. things like archer, sharpshooter, hunter, flintlock, cannonier, etc. are practically all just ranger in the terraria system? some might be a bit of a hybrid, like paladdins can heal to a small extent, so they're not pure melee. but in general, almost everything can be placed somewhere within that system, but Geomancer is a bit unique. it's partly a mage with a bit of melee mixed in (the batons), but utilising the biomes still sounds something no other classes do.
in theory, it could encourage players to alter areas here and there based on what biome spells they would prefer to use - e.g. at boss arenas.
though later game, you also could just use the enchanted bottles.
but a full class needs like 7-8 armors and around 30-40 weapons at minimum, right? and a few accessories too. it would be a huge thing to do. and we don't even have much ideas for it, but I think we might can use it for something at some point. as for one, we might can try to make the batons work, if we can (maybe for now, just for melee), because right click functionality sounds fun. and weapons like that could be convinient to reach to a bit more distance, yet still have the arc attack too, that swords have. (if so, their attack should be a bit lower than swords of the same type, to compensate for it)
but I'm just thinking loud, I guess XD