316.2.b. This is denoted as a Neutral Open State, and only the Turn Player has the ability to play spells or activate abilities. See rule 307. States of the Turn for more information. 316.2.b.1. In Modes of Play with teammates, the Turn Player's teammates may play spells and activate abilities, including ones without Action or Reaction. They can only do so when the Turn Player invites them to do so with their own Priority.