The Charisma save allows a player to prevent the possession entirely if they don't want it. That only happened twice in my playthrough - the rogue attempted and failed to keep Obo'aka out, and the bard succeeded keeping Papazotl trapped in his amulet, which the bard then could use freely.
As for class-restricted attunements, we ran into that as well. Our bard was the first to touch Moa's staff. Although he couldn't wield it due to his class, the act of touching it triggered the inhabitation, which he allowed. He then gave the staff to my cleric to use.
Finally, the module doesn't allow characters to "swap" spirits. It's pretty explicit about saying the gods don't willingly leave their host. They can, however, be forced out in a few ways: if the host dies, if the host leaves the tomb, or if someone casts Dispel Evil and Good on them. They can also be forced out if another spirit tries to inhabit the same host, and the DM rolls to determine the outcome. And once a god leaves a host, they can't re-inhabit that host for the rest of the adventure.
I am preparing to run ToA and I realised that some of the magic items like Shagambi’s mandolin can only be attuned to by a certain class.
What would happen if a character touched the mandolin and was not part of the class?
If there is no connection to the attunement and the spirits then how would the Relics of the Past section work?
And if rhe characters can swap spirits then why are there Charisma saves?
The Charisma save allows a player to prevent the possession entirely if they don't want it. That only happened twice in my playthrough - the rogue attempted and failed to keep Obo'aka out, and the bard succeeded keeping Papazotl trapped in his amulet, which the bard then could use freely.
As for class-restricted attunements, we ran into that as well. Our bard was the first to touch Moa's staff. Although he couldn't wield it due to his class, the act of touching it triggered the inhabitation, which he allowed. He then gave the staff to my cleric to use.
Finally, the module doesn't allow characters to "swap" spirits. It's pretty explicit about saying the gods don't willingly leave their host. They can, however, be forced out in a few ways: if the host dies, if the host leaves the tomb, or if someone casts Dispel Evil and Good on them. They can also be forced out if another spirit tries to inhabit the same host, and the DM rolls to determine the outcome. And once a god leaves a host, they can't re-inhabit that host for the rest of the adventure.