How would I go about creating a freaky friday effect, usable by a player.

[Oxylepy]

So this is effectively his end goal as a player and his desired capstone for his character, which I'm fine with assuming the targets get a save to avoid the effect. But how do I go about doing this effect. Essentially his desire is to magic jar/freaky friday other people for the hilarity that would ensue.

But is there some kind of spell that can achieve this? Or an artifact? Precidence would be wonderful because as it stands the only close effect would be the juju oracle's capstone, which is problematic in requiring the casting of a school spell to achieve it (in this case I want to avoid dependancy upon a specific school of magic as it would be extremely painful to his character build).

[Gwaihir Scout]

That sounds exactly like mind swap from Occult Adventures, which is at worst a sixth-level spell. It gives a Will save and lasts for hours.

There's a ninth-level version that's permanent, but it's expensive and psychic-only. You didn't say what class this player is using, but a new capstone that lets him use major mind swap seems to be what you're looking for.

[Oxylepy]

YES that is exactly what I was looking for. Swap it to two targets instead of yourself, make it uses per day and I can even level it up gradually which is how I want all the class abilities to work. Excellent. Thank you.

As for the class, it's a homebrew I'm working on. But that effect works perfectly for what he wants to pull off, just with targets instead of himself. Give it as a 3 uses a day at 20th targeting 2 creatures, use all 3 to do 1 creature/2 caster levels no two of which more than 30' appart. Boom, have it level up from possession and add it to the group of effects which are limited to 1 for the character (putting it on par with a +2 CR template such as lich/graveknight/animal lord).