Hallan, Lunaris Guardian

Ethereal
When Hallan, Lunaris Guardian enters the battlefield, the next noncreature spell you cast
this turn costs {2} less to cast.
When Hallan, Lunaris Guardian becomes the
target of a spell or ability an opponent controls,
you may exile Hallan. If you do, return it to the battlefield under your control at the beginning of
your next upkeep.