Book of Shadows: Shadow Form

Shadows rise from the ground to envelop you and they pull you into their depths enveloping you.

The subject of this spell turns into a natural shadow. The subject can move at a speed of 30 feet along any surface, including walls and ceilings. The target must remain adjacent to a surface for the duration; it cannot enter into areas of supernatural darkness or supernatural brightness ( for example daylight spell). While in this form, the creature gains a bonus to Stealth checks while in dim light or darkness equal to your caster modifier (maximum +10).
The creature can also turn itself back and forth from shadow form to its normal material form as a full-round action. Each time it returns to its normal form, the duration of the spell is decreased by 2 minutes.

The subject gains these additional benefits well well in shadow form:

Amorphous. The subject can move through a space as narrow as 1 inch wide without squeezing.

Melt Into Shadow. A subject can dissolve into a dark patch on the ground. In this form, the subject cannot attack or be attacked, but it is still aware of everything that is happening. This ability may be used as a move action

Shadow Stealth. While in dim light or darkness, the subject can take the Hide action as a bonus action.