Dilation Sphere

A 5-foot-radius semi-transparent sphere of glowing blue energy grows into existence centered on a point you choose within range and remains stationary for the duration. When you cast the spell, choose one of the following effects. Once the effect is chosen, it persists until that instance of the spell ends. 

Acceleration. Time within the sphere flows at double the relative rate of the outside. All matter inside the area will experience 2 hours for every 1 hour outside. If used during combat, Creatures within receive 2 combat turns for every round occurring outside. Creatures within the area will have advantage on hitting creatures outside, due to their targets moving and reacting at half relative speed. The inverse is also true. Creatures outside the area will have disadvantage on hitting creatures inside, due to their targets moving and reacting at double relative speed. 

Deceleration. Time within the sphere flows at half the relative rate of the outside. All matter inside the area will experience 1 hour for every 2 hours outside. If used during combat, creatures within receive 1 combat turn for every 2 rounds that occur outside. Creatures within the area will have disadvantage on hitting creatures outside, due to their targets moving and reacting at double relative speed. The inverse is also true. Creatures outside the area will have advantage on hitting creatures inside, due to their targets moving and reacting at half relative speed. 

Creatures and objects can move through the sphere freely. If passing through the trap without ending your turn within, movement distance per turn can also be accounted for. Movement within an acceleration trap costs half of what it would normally, due to the faster dilation. Movement within a deceleration trap costs double of what it would normally, due to the slower dilation.

Spells and other magical effects can also extend through the sphere and be cast through it, but all of the spells effects will experience the same time dilation. Saving throws can be affected at DM discretion. Time passes normally to creatures within the area, and all game rules regarding exhaustion or anything related to the passage of time should be considered individually from the external world.

The spells area can overlap with the area of another Dilation Sphere spell of the same type. Only the area is expanded, the effect remains the same. If you cast Dilation Sphere every day for 30 days in the same location, the spell lasts until it is dispelled.

At Higher Levels. For each level you choose to cast above 4th level, the duration increases by 1 hour. Additionally, you can increase the radius of the sphere by 5 feet per level.