Immediately when you stop casting the spell, time freezes in the world around you, and you create a divergent timeline that you are able to live through. Events play out as they would if you hadn't cast this spell, but you are in a temporary world. You are able to live through this world, discovering what would happen if you took a certain set of actions. The spell ends if you die in this alternate timeline, or until you use an action to return to your real timeline. 

If you gain any levels while under the effect of this spell, you lose them when this spell ends. Any objects you grab or interact with are returned to their original position before you cast this spell. You appear in this timeline in the same condition you were before you cast this spell, holding and wearing everything you had on your person before. Nothing about the world around you changes when you cast this spell, everything appears to be the same and you can interact with the world as usual, but after the spell ends any changes you made to the world around you are undone. 

If you take any damage in this alternate world, you don't take it in the real world, and your real form is not damaged or changed at all when you cast this spell. No changes to the world you make while under the effects of this spell are real, all of them stop after you cast this spell.