Lullaby Singer

Flying
If it's neither day nor night, it becomes day as
Lullaby Singer enters the battlefield.
Whenever day becomes night or night becomes day,
tap target creature. If it is your turn, put a stun
counter on that creature.
Aurora {2}{u}{u} (You may cast this spell for its
Aurora cost. When you do, it becomes day if it is
night, otherwise it becomes night.)
When Lullaby Singer is cast for its Aurora cost, tap
target creature and put a stun counter on it.