the infinity castle has only 4 things that muzan quest to lvl 55, muzan that upgrade you to be a stronger demon at lvl 90, the guy with the hallowin demon art and the 3 teleports. you could add 1 muzan that if you talk to him he will give you some options like to do some quest or upgrade or somethings and this will be enough. add douma house, kokoushibo in his place with the strange things, where muzan did experiments at the first ep of season 3 that by the way good place to muzan in the game and all upper moons and the dead lower moons and also instead this 3 purple teleports you can add NPC of nakime that ask you where do you want to travel and you have there 3 option aki village, rice field and minu village.
#DSRPG3 and DSRPG2: add some another stuff at infinity castle
novel flame