Temporal Flow

You can transfer the flow of time from one creature to another within range, speeding up one while slowing down the other. An unwilling creature must make a Wisdom saving throw when you cast the spell, ending the spell on a success. Otherwise on a failed save it recieves one of the effects by this spell for the duration, and can repeat the saving throw at the end of each of its turns.

When the spell ends on one creature, the spell ends. 

Choose one effects below for one of the creatures targeted, whatever effect you do not choose the second creature receives that one:

Speed Up. The creature increases its movement speed by 10 feet and gains an additional attack on each of its turns. The creature receives a +1 to its AC and Dexterity saving throws. 

When the spell ends early the creature that has this benefit receives "Slow Down" effect of this spell until the start of the caster's next turn.

Slow Down. The creature decreases its movement speed by 15 feet, can only take either an action or a bonus action on each of its turns regardless of the creature's abilities or magic items it can only make one melee or ranged attack a turn. The creature receives a -2 to AC and dexterity saving throws.

If the creature attempts to cast a spell with a casting time of 1 action, roll a d20. On an 13 or higher, the spell doesn't take effect until the creature's next turn, and the creature must use its action on that turn to complete the spell. If it can't, the spell is wasted.

When the spell ends early the creature that has this benefit receives the "Speed Up" effect of this spell until the start of the caster's next turn.