Your king puts on sunglasses for the rest of the game (purely decorative) and cannot be captured for your opponent's next 2 turns. Nobody recognizes him. Everybody recognizes him.
You draft Royal Incognito in either mode. Instant: it takes effect the moment you draft it.
As a item card, it is a one-use consumable, drafted in either mode.
“Just a regular citizen, out for a stroll, worth the entire game.”