Discard Pile Visibility

• According to page 12, "Discarded cards are piled here, face-up. You may look at them anytime but never change their order."
• This means both players can look at the opponent's discard pile at any time.

Order of Cards in the Discard Pile

• The same section specifies that the order of cards in the discard pile cannot be changed.
• For simultaneous effects, page 22 states: "When this happens, the current player decides the order in which the abilities are resolved."
• Therefore, if multiple cards are discarded or destroyed at the same time, the current player decides the order in which their effects are resolved, which would also determine the order in which they are placed in the discard pile.

Summary:

• Players may look at the opponent's discard pile at any time, but cannot change the order of the cards.
• When multiple cards are discarded simultaneously, the current player decides the order in which they are placed in the discard pile, based on the order of effect resolution.

Sources:

• page 12 (Discard Pile Area visibility and order)
• page 22 (Simultaneous Effects and order resolution)

Source: Core Rulebook (pp. 12, 15, 17, 18, 22)