Timeslip

You transport yourself back in time by any amount of time of your choice that is less than 5 rounds (30 seconds).
Your mind and soul are transferred to your body from the chosen time ago, complete with the equipment it had at that time. No duplicate bodies or items are made.
When the time travel is complete, each creature except you is unaware that the travel had been made. Until they are influenced or interrupted by you or anyone already influenced by you, they will make the same decisions they made that amount of time ago, and those decisions will bear the same consequences. Once the amount of time elapsed after the travel exceeds the amount of time travelled back, the flow of time will have been caught up, creatures will begin to make new decisions at their own will.
The material compenent of the spell is a sizeable amethyst crystal, valued at around 150gp, of which is shattered in the casting process. When travel is complete, the used crystal, wherever it was at the destination time, forms cracks and becomes unusable as a material component.
When you cast this spell using a spell slot of 7th level or higher, the maximum amount of time you can transport yourself back is increased by 5 rounds for each level above 6 this spell was cast at.