Dreamwalking

As a warning, spoilers ahead for Dr. Strange and the Multiverse of Madness. If you haven't seen it and don't want to be spoiled, you might want to come back after having watched the movie.

To anyone else, this is my attempt at taking the Dreamwalking spell used in the movie and porting it to D&D. It says 9th level, but I think this would be way higher but I'm not actually sure how to actually gauge a power as wacky as this one. If you have any feedback or changes you'd make I'd like to hear it and see what anyone else thinks. I can't really see a reason to cast this spell especially since its so high level but I wanted to try my hand at applying D&D mechanics to it and trying to see how this could fit in a D&D universe if anyone is daring enough. Enjoy.

Having spent immense time studying, testing and understanding the multiverse and its timelines, you have found a way to manipulate the Weave not only in your own universe but can use that to connect to the Weaves of other universes. With this connection, you can possess an alternate version of yourself, and the infinite other existences you have laid out across the multiverse. Either at random or by choice of your DM, you possess another version of yourself in an alternate universe. You can choose a version of yourself to possess if they have been taken over by you before. You have full control over that version of yourself for 24 hours. All of your powers do carry over to that other version of you for the duration as do your ability checks, ability scores and bonus to saving throws, however, using a power that is too strong for that copy can have lasting effects and dire consequences once the possession ends. This includes spells that are cast at a level higher than what that you is capable of or would be capable of, using a class feature that is unlocked at a level that is higher than your copy, or by simply being too powerful. For every 2 levels higher you are than your copy, the creature takes 1 level of exhaustion, up to a maximum of 5. If you cast a spell that is higher than what that copy is or would be capable of casting, they take a -1 bonus to their Intelligence, Wisdom and Charisma saving throws. They gain +1 back for every long rest they take after possession. For every feature you use that they can't or would be incapable of using, they take a -1 to their Strength, Dexterity and Constitution saving throws. They gain +1 back for every long rest they take after possession. Other consequences may occur at the discretion of your DM. If the copy you are possessing has these negative effects as a result of a recent usage of this spell, they count against your scores until that copy fully recovers from these side effects.

Once connected to your alternate self, you are able to wreak as much havoc or do as little as possible as you are capable of. However, this also affects your original body in your original universe. Any pain you experience, any damage you take and every feature and spell you use while in possession is also used when the possession ends. In the event that you die while in the other universe, you must make a DC 25 intelligence saving throw. On a success, you still die but your soul returns to your original universe in the plane you are currently on. On a failure, your soul is trapped in that universe, and the only way to be brought back is to have someone revive you there.

When connecting yourself to another universe for the first time, there is a 5% chance of an incursion occurring. Constantly visiting another multiverse causes this to go up an additional 5% per visit. This chance is unique to that universe, and every universe has a different chance of an incursion happening based on however many times a person from your universe has connected to themselves in that universe. When an incursion is rolled, both universes begin attracting to each other. When the universes eventually collide it will wipe out the entirety of both universes and they will cease to exist. This includes all matter, life, magic, etc. Anything that existed in both universes will cease to be including the timelines each of them generated. This is permanent and cannot be reversed, even by the wish spell. 

While you are in possession of your other self, you are entirely unaware of your surroundings. You are blinded and deafened. Additionally, any attacks made against you are at advantage, and when a melee attack made within 5 feet of you hits, it is a critical hit. When your original body takes damage, you don't feel it in the possessed body. Additionally, though you can concentrate on spells using your copy, this spell requires the concentration of your original body. You must make Constitution saving throws using the possessed copy's Constitution saving throw score. On a failure, you are forcefully pulled out of the possession. When this happens, you immediately take 1 level of exhaustion, and you cannot connect to another universe for 30 days. If you choose to end the spell early, you are safely returned to your original body with no consequence.