Guise, You Know Who I Am

{3}: Guise, You Know Who I Am becomes a copy
of target creature until end of turn, except its
name is still Guise, You Know Who I Am and
it is legendary.
When Guise, You Know who I am dies, your
opponents may cheer for its death. If at least one opponent does not, the next commander spell
you cast costs twice (X) less to cast, where (X) is
the number of times your commander has been
cast from the command zone this game.