Coronet, Monarch of Mimicry

Hidden in Sight —Replace all instances of the
phrase "at the beginning of your" with "at the
beginning of each opponent's" in the text of
permanents you control.
Gone at Night—{w}{u}{g}, {t}: Coronet, Monarch of
Mimicry becomes a copy of an artifact you control,
except it retains its abilities. Activate only on an
opponent's turn.

"Wait, where did the crown go?"
—A castle guard