Dune
What can I ask with Truth Trance, and when can I play it?
Any yes-or-no question about the game, at any time, even for an ally or in a battle you aren't in; it reveals things you couldn't otherwise learn. The card is discarded after use. Questions about the opponent's hand are fine, while questions about future actions are contested: the GF9 FAQ, as quoted, allows near-term ones such as the current turn's shipment.