Time Dilation

You create a rift in fabric of time, engulfing all creatures within range. Each creature in a 10-foot-radius Sphere centered on a point within range must make a Wisdom saving throw or take 4d12 psychic damage and suffer the following effects. When you cast the spell you can decide whether the rift will send creatures forwards or backwards in their timestream. A creature that succeeds the saving throw takes have as much damage and suffers no additional effects. The target makes a Wisdom saving throw at the end of each of its turns, ending the effect on itself on a success. 

Forwards in Time. The creature is sent forwards in their timestream. They suffer the following effects:

• Disadvantage on Constitution saving throws to make to maintain concentration on a spell or other magical effects.
• The creatures speed is halved.

Backwards in Time. The creature is sent backwards in their timestream. They suffer the following effects:

• The creature deals only half damage with attacks that use Strength.
• The target has Disadvantage on Strength checks and Strength saving throws.

Using a Higher-Level Spell Slot. The damage increases by 1d12 for each spell slot level above 4.