DESC: At will your body is only partially solid in an undulating fashion. This is due to being in a fluxed dimensional state, ethereal or gaseous. Other causes of your insubstantial nature can be defined for your race as long as it fits the benefit given.
This does not grant you a ability to pass through walls, doors, or even cracks as some part of your body is still solid at any given moment, even at a 100% miss chance. The higher the miss chance is simply better control of what portion of your body is insubstantial.
This power is only effective verse physical attacks directed at you. This does not protect your mind. Nor does it protect against area effect spells.