This is a very cool Boss design and I love how the fight changes (As well as the Dungeon enemies) depending on what type of Dark Biome Your World has.
With 1.3 I'd actually like to see both Fishron and Golem be a gate to this boss (meaning both have to be defeated, to prevent an exploit of a player beating Fishron early Hardmode). Having this boss serve as the boss before fighting the Cultists sounds very good as well. It seems like having this boss be the last boss before the Lunar seems more appropriate from a story/lore perspective because it's like an important leader of the Cultists has been defeated which requires them to take action. Also to encourage more different visits to the Dungeon and to extend the game's length even more. And giving a new area of the Dungeon that can't be explored until the player fights this boss leaving the player to wonder what could be behind this locked area similar to the Jungle Temple.
You have my support!
With 1.3 I'd actually like to see both Fishron and Golem be a gate to this boss (meaning both have to be defeated, to prevent an exploit of a player beating Fishron early Hardmode). Having this boss serve as the boss before fighting the Cultists sounds very good as well. It seems like having this boss be the last boss before the Lunar seems more appropriate from a story/lore perspective because it's like an important leader of the Cultists has been defeated which requires them to take action. Also to encourage more different visits to the Dungeon and to extend the game's length even more. And giving a new area of the Dungeon that can't be explored until the player fights this boss leaving the player to wonder what could be behind this locked area similar to the Jungle Temple.
You have my support!