Empty air sandwich
Terrarian
In expert mode only,
1) Bosses that already were defeated once (or maybe all) can scale up in stats depending on the current world progression (specifically which bosses ahead of it were already beaten). Not as to make them stay the exact same difficulty forever, more just to help stop them from getting so stompable it's not even fun anymore. (like, significant HP increase, DEF barely higher if at all, damage needs to be increased much less the higher it already was)
Something like, Eye of Cthulhu is LV2 after beating Eater/Brain, LV3 after Skeletron, LV4 since hardmode, LV5 after all 3 mechs, LV6 after Golem, LV7 after Moon Lord. (the impact of every change doesn't need to be very consistent per change)
Bosses that can scale: Eye of Cthulhu, Eater/Brain, Skeletron? (only fought once anyway), Queen Bee, Wall of Flesh, 3 mechs, and, Fishron&Plantera&Golem maybe only once after Moon Lord
Maybe a few also get tweaked behavior after a certain level if it would be important (namely King Slime Deluxe being less cheatable, like being able to do a super jump if you're too high for its regular jump loop, this one having a much higher maximum altitude and can rise through blocks. DX Golem maybe could get harder to hit in phase 2, like getting small moving barriers around itself or yellow-deviling sometimes with its megazord parts and being unhittable during it).
2) Now with the scaling, maybe some bosses have additional expert mode unique drops you can only get by re-fighting their higher-level versions, and/or they can drop number-enhanced versions of some of their old equipment, them being allowed higher stats because those can't be obtained until later anyway (like at least Eye of Cthulhu later dropping higher-damage versions of its dash shield, and a few boss weapons/accessories dropping upgraded versions from the DX boss, like the bee/wasp guns maybe needing stronger versions later especially because of expert's higher enemy DEF), dropping as the raw drop from the boss or as added crafting material drops from the boss to upgrade the originals, like Expert Boss Souls.
3) I remember someone posting in one of Chippy's videos that expert Moon Lord could also drop an item that if carried triples-ish the HP of all bosses. So like one that puts every boss on an absolute supermax level here including Cultist & Moon Lord which I was thinking don't even level up normally, like an extra challenge mode after beating the game that doesn't even need "new" content. Maybe for this item to work you need to do all supermax bosses in order one by one, initially only working for Eye of Cthulhu then working your way up to working on all, finishing with higher-level Moon Lord himself, with the item always saying in its tooltip the next needed boss on its list. The max bosses keep all previous DX drops and maybe there's a few more here too or not. If you wanna get crazy, the supermax item might be an equippable accessory and it does nothing but gets powerful various attributes like an almost godmode/debuggertool item once you finish everything, or just gets a passive vanity effect, like a badge.
4) Also, expert mode by itself could change boss&mimic drops to drop more than 1 of its weapon/accessory it always drops, like always 2 or it's randomly 1 or 2, or 1 or 2 or 3, with the scaling improving the rates. This is so that, even now if you wanted normal drop X of a boss like a certain weapon and your main world was expert, with this you would actually have positive reasons to keep farming the boss in the expert version from getting more than 1 per kill, instead of thinking to go to farm the same boss in a normal world because there you would spend the same amount of boss summoners, do it faster and easier, and still have the exact same odds of getting the item you want because both are 1 per kill. You can do whichever you want for that but the incentive existing would be good.
(4.5: also, I think mimics could use having their grappling hook drop be made as a separate chance just for the hook instead of the hook taking up a slot of its single guaranteed drop, would be better as separate because it tends to show up as the only drop and kill the fun of mimic treasures. By the time you can find mimics you're not really craving for any hooks anymore)
1) Bosses that already were defeated once (or maybe all) can scale up in stats depending on the current world progression (specifically which bosses ahead of it were already beaten). Not as to make them stay the exact same difficulty forever, more just to help stop them from getting so stompable it's not even fun anymore. (like, significant HP increase, DEF barely higher if at all, damage needs to be increased much less the higher it already was)
Something like, Eye of Cthulhu is LV2 after beating Eater/Brain, LV3 after Skeletron, LV4 since hardmode, LV5 after all 3 mechs, LV6 after Golem, LV7 after Moon Lord. (the impact of every change doesn't need to be very consistent per change)
Bosses that can scale: Eye of Cthulhu, Eater/Brain, Skeletron? (only fought once anyway), Queen Bee, Wall of Flesh, 3 mechs, and, Fishron&Plantera&Golem maybe only once after Moon Lord
Maybe a few also get tweaked behavior after a certain level if it would be important (namely King Slime Deluxe being less cheatable, like being able to do a super jump if you're too high for its regular jump loop, this one having a much higher maximum altitude and can rise through blocks. DX Golem maybe could get harder to hit in phase 2, like getting small moving barriers around itself or yellow-deviling sometimes with its megazord parts and being unhittable during it).
2) Now with the scaling, maybe some bosses have additional expert mode unique drops you can only get by re-fighting their higher-level versions, and/or they can drop number-enhanced versions of some of their old equipment, them being allowed higher stats because those can't be obtained until later anyway (like at least Eye of Cthulhu later dropping higher-damage versions of its dash shield, and a few boss weapons/accessories dropping upgraded versions from the DX boss, like the bee/wasp guns maybe needing stronger versions later especially because of expert's higher enemy DEF), dropping as the raw drop from the boss or as added crafting material drops from the boss to upgrade the originals, like Expert Boss Souls.
3) I remember someone posting in one of Chippy's videos that expert Moon Lord could also drop an item that if carried triples-ish the HP of all bosses. So like one that puts every boss on an absolute supermax level here including Cultist & Moon Lord which I was thinking don't even level up normally, like an extra challenge mode after beating the game that doesn't even need "new" content. Maybe for this item to work you need to do all supermax bosses in order one by one, initially only working for Eye of Cthulhu then working your way up to working on all, finishing with higher-level Moon Lord himself, with the item always saying in its tooltip the next needed boss on its list. The max bosses keep all previous DX drops and maybe there's a few more here too or not. If you wanna get crazy, the supermax item might be an equippable accessory and it does nothing but gets powerful various attributes like an almost godmode/debuggertool item once you finish everything, or just gets a passive vanity effect, like a badge.
4) Also, expert mode by itself could change boss&mimic drops to drop more than 1 of its weapon/accessory it always drops, like always 2 or it's randomly 1 or 2, or 1 or 2 or 3, with the scaling improving the rates. This is so that, even now if you wanted normal drop X of a boss like a certain weapon and your main world was expert, with this you would actually have positive reasons to keep farming the boss in the expert version from getting more than 1 per kill, instead of thinking to go to farm the same boss in a normal world because there you would spend the same amount of boss summoners, do it faster and easier, and still have the exact same odds of getting the item you want because both are 1 per kill. You can do whichever you want for that but the incentive existing would be good.
(4.5: also, I think mimics could use having their grappling hook drop be made as a separate chance just for the hook instead of the hook taking up a slot of its single guaranteed drop, would be better as separate because it tends to show up as the only drop and kill the fun of mimic treasures. By the time you can find mimics you're not really craving for any hooks anymore)
