If an effect would compel a player to perform an action on cards whose privacy is secret or private, and if that effect specifies a type or quality of card, the player in question may choose to ignore that instruction. Ignored instructions are deemed impossible.
§ 128.6.a Core Rules PDF (officieel)
§ 128 Privacy
§ 128.6 A player cannot be compelled to perform an action on cards whose privacy is secret or private if that action specifies a type or quality of card. Example: A card effect reads, “Play a unit from your hand, ignoring its costs.” Although the effect does not say “may”, the player can choose not to perfor…
