Insubstantial

From the Rulebook:

Player may not interact with game items, objectives, or other players unless specified by the ability that made them Insubstantial, other than retrieving equipment. Players may only target themselves with magic and abilities that are able to affect insubstantial players. May use Meta-Magic and Charge abilities. Insubstantial players:

1. May not move from their starting location unless unless specified by the ability that made them Insubstantial. This is different from Stopped in that you can still move your feet.
2. Can only be affected by mechanics that work on States in general (such as Release) or Insubstantial in specific (such as Dimensional Rift). Player and their carried equipment are otherwise unaffected by combat, abilities, etc.
3. Are not affected or stopped by game terrain such as walls, lava pits, traps, etc unless otherwise indicated by the reeve or game designer.
4. May remove this State from themselves at any time by Incanting “I return to the physical world” x2 provided they are the cause of the State and the State was not imparted by an Enchantment. Otherwise, they must end the State as per the description of the responsible ability. This incantation is not interrupted by the player moving their feet, and does not require a free hand.
5. Must indicate their Insubstantial State by saying “Insubstantial” if asked, attacked, or targeted by an ability.
6. May not delay the game excessively. For instance, you may not use this State to avoid being killed if you are the last player alive in a Mutual Annihilation battlegame. The reeve's decision is final.

Rulebook 8.6.3

FAQ

Common Reeving

The following is not an official part of the Rules of Play, or an Official Clarification, but is a common way Reeves have ruled on particular issues. It is provided for a reference only, and the final decision, as always, remains with the ruling Reeve.

Can someone use Release to force me out of Insubstantial?

Because Release has a range of Touch, per the Range rules, someone cannot use Release against an unwilling target in this way unless the insubstantial target is also unable to move, such as being affected by Astral Intervention, because by default an insubstantial target is Stopped. An insubstantial target can almost always be targeted with Greater Release, however.