Coin of Fate

A Coin of Fate is a magical item with the power to split time in two. The coin can only be used when one must make an important decision, one which they could decide either way. Each option is assigned to one of the sides of the coin. Once assigned, the user then flips the coin and then must follow through on the decision corresponding to the result of the coin flip. The timeline is then severed in two, the true timeline which the user is still experiencing, and a false one in which the user had gotten the opposite result. The false world user, along with all other beings in the false world, will be unaware of the fact that their reality is false and will "have forgotten" about the coin's magical properties, believing themselves to have just left the decision up to chance, and go about their existence living with the decision's consequences with the coin that they have in their possession being completely mundane. Meanwhile, the user in the true timeline can at any point flip the coin again, at which point they will "awaken" as their self in the false timeline. The False timeline then becomes the true timeline and the previous true timeline collapses, ceasing to exist. The original Coin of Fate, along with the rest of the users belongings, do not transfer over to their parallel false world self when the change timelines.
It is possible for the user to preview the false timeline through scrying, though such readings are very difficult and prone to giving misinformation. Once the user transfers, they will quickly relive all of the experiences their false world self has had up until a time after the flip corresponding to how much time passed before they flipped the coin again. They will not be able change any of the actions or decisions that their false self made after the results of the coin flip.
The false timeline can only exist for a limited amount of time after creation, depending on the power of the coin, and once its time limit has ended, it will cease to exist and flipping the coin a second time will no longer transfer the user to the false world. Most coins are expended after one use, even if the user does not change timelines.
== Variants ==
Their exists a more powerful variant that transfers the user backwards in time in the false universe, to the moment after getting the results, and an even more powerful version that transfers them to before they even decided to flip the coin, allowing them to make their decision again freely.
The Grey Man is believed to use even more powerful artifact variants that create persistent alternate universes and allow him to travel between them freely.