Public, private, secret and derived information

The rules sort information into levels. For cards there are three: Secret, where no player may read the face of the card, Private, where only the controller of a card on the board or the owner of a card elsewhere may, and Public, where any player may (rule 128.3, rule 128.4 and rule 128.5). A card's level is normally that of its zone (rule 128.2.a). The Play Area is public: any player may look at the face-up information on cards there, and the state of every game object in it, such as whether a unit is buffed or a gear is exhausted, is public too (rule 109, rule 109.1 and rule 109.2). The tournament rules add a fourth level. Derived information is public information combined with a player's own skill or calculation (TR 502.2 and TR 502.2.a).

The mistake to avoid is treating "I would like to know it" as "someone has to tell me". The Tournament Rules answer the two cases differently. Public information must be answered honestly and never misrepresented, and judges are encouraged to help you find it (TR 502.7, TR 502.8 and TR 502.10). Derived information also must not be misrepresented, but your opponent is not required to help you work it out, and judges are encouraged to help with public information but not with derived information (TR 502.2.b and TR 502.10). A floor judge may still answer questions about derived game state (TR 204.5.a), but at high OPL (Organized Play Level) not a direct question about the result of an action you have not yet taken, so you ask about the rules instead (TR 204.5.a.1). The current score, the number and kind of resources in a Rune Pool, the cards and choices on the chain and each permanent's current state are all public (TR 502.4.c, TR 502.4.d, TR 502.4.e and TR 502.4.f). Which public cards have been recycled, and what a unit's Might would be if a player attacked with it, are derived (TR 502.5.a and TR 502.5.c). Private information, such as the cards in a hand, need not be shared, and a player may bluff about it (TR 502.11).

Here is a worked example. Dana controls a unit with Shield 2 and her opponent, Eli, asks, "What is it going to be if I attack?" Dana's unit is public and its printed Shield is public, but the Might it would have as a defender (rule 814.1.c) is a consequence of an action that has not happened, so it is derived: Dana need not do Eli's arithmetic, and at a high OPL event a judge would not do it for him. But if Eli asks how much Energy she has floating, she must say, because that is public (TR 502.4.c and TR 502.7).

The back of a card does the work of hiding. There are three back patterns: Main Deck cards, Rune Deck cards, and Battlefields together with Champion Legends (rule 129.2). A card shown on its back is presented to conceal Private or Secret information, and "facedown" means a card on the Board with its back showing, whose front is Private (rule 129.3 and rule 129.4). A card shown on its front is Public, even when part of a pile hides it, which is why the trash can be looked through (rule 130.5 and rule 130.6). One wrinkle is that a battlefield's Facedown Zone is a Public Zone while the card inside it is Private (rule 107.3.f). Players must also make a reasonable effort not to reveal secret information by accident (TR 424.2).

Information errors are Warnings. Looking at information that no player may see, such as flipping over the top card of a Main Deck, is Looking at Secret Information, and the remedy is to re-randomize the cards with the original randomized source, or, if that is not possible, to reveal the information to everyone (TR 702.10 and TR 702.10.b). Accidentally looking at an opponent's private information is Looking at Opponent Private Information, and the opponent decides whether the now-known cards are re-randomized (TR 702.11 and TR 702.11.b.1). In both cases you are not penalized for an error your opponent made, so if they drop a card face up and you see it, you get no penalty (TR 702.10.a and TR 702.11.a). Putting a card into a facedown zone, or taking one out, in a way the Core Rules do not allow is a Facedown Card Error (TR 702.13).