Alter Time

This spell causes a creature to act either earlier or later in combat. An unwilling creature must make a Constitution saving throw to avoid the effect. On a failed save you can choose to make the creature shift in initiative order by one place, acting either before the creature with the next highest initiative, or after the creature with the next lowest initiative. If this change in initiative would cause the creature to miss its turn, it acts immediately. This will be the new initiative until combat is over or until initiative order is altered again. 

At Higher Levels. When you cast this spell at 4th level or higher, you can move the target's new initiative order by 1 additional spot.