Ghosts in Innistrad
The savage reality of Innistrad leads to many restless human spirits, called geists. Such spirits may be lost between life and the Blessed Sleep, lingering bent on resolving unfinished conflicts, or protective ancestors who remain to watch over their children. Geists exist in a state just beyond the material realm, and are fundamentally insubstantial, able to reach through walls, disappear, or float motionlessly in the air.
While geists are insubstantial, they are not incapable of harming humans. Many can turn themselves substantial for an instant, long enough to lash out with ghostly fetters or smoky claws, others can wield material objects psychokinetically. Geists unable to directly affect the material may be able to psychically attack human minds, either misleading them with illusions, or making people so thoroughly believe that they are being wounded that they suffer real damage. The ability to possess mortal forms or empty vessels, such as skaabs or geists, and manipulate temperatures and ambient light are nearly ubiquitous.
A Blue or White character may have a geist bound to their body which they can tap into draw on the benefits of incorporeality. A Geistbound character may take a standard action to benefit as if under the effect of the blink or gaseous form spell. Alternatively, they may take an immediate action to gain the ability to turn one part of their body incorporeal. This ability lasts 8 rounds, and they may change the part of their body that is incorporeal each round. Any item held or worn on the part of their body that is incorporeal is also incorporeal, and the character may spend two rounds of use to turn both hands/arms incorporeal for one round.
Being Geistbound takes up a permanent magic item slot and is considered a Medium magic item.