Phasing

Phasing is the ability to pass through solid matter. It is similar to Density Control, except that it only allows oneself to lower density, rather than increase it.

It is also similar to intangibility, except that not every intangible being is able to pass through solid matter. For example, someone with the ability to transform into gas is rendered untouchable, but they are not capable of passing through solid matter. Phasing strictly involves the passing through solid matter.