Halfdane the Ever-Changing

Halfdane the Ever-Changing enters the battlefield
as a copy of any creature on the battlefield,
except its legendary in addition to its other types
and gains "At the beginning of your upkeep
destroy all other creatures with the same name as
this creature, then exile this creature and return
it to the battlefield under its owner's control."
All those in Tolaria fear something that they have
never seen before.