Clockwork Field

An invisible cylindrical area of clockwork law from the plane of Mechanus appears centered on a point within range. Within this area, all dice rolls made must use their average rolls, for example, a d20 would always roll 10, or a 3rd level fireball would always deal 28 damage. All rolls keep their modifiers which are added to the averaged rolls. Percentile dice and their effect tables (like those of wild magic surges) also automatically roll a 50.

This spell automatically fails if cast within the plane of Mechanus, however the spell slot you used to cast it will not be expended.

On each of your turns after you cast this spell, you can use an action to move the field up to 30 feet in any direction.

Targeted Projectiles. Projectiles and targeted magical effects, such as arrows or magic missile spells are only subject to the field's effect if it hits a creature or object that is within the field. Ones that pass through the field to hit a target on the other side/outside of the field will not be affected and roll normally once it exits the field. 

Areas of Effect. The portions of other areas of effects that extend into the cylinder must also use their average rolls. For example, the part of a fireball that extends into the field would deal its average damage while the part of it that is not inside the field will roll as normal.

Creatures of Chaos. A creature native to the plane of chaos, Limbo, winks out of existence in the field. Such a creature instantly reappears once the space the creature occupied is no longer within the area of the cylinder.

At Higher Levels. For every 2 levels you upcast this spell, the radius of the field increases by 5 feet, at 6th level increasing to 15 ft., and at 8th level increasing to 20ft.