The Winged Dragon of Ra

Flying, vigilance
Split second
When this creature enters the battlefield if it was
not cast, exile it.
When you cast The Winged Dragon of Ra
you may pay life until you have 1 left,
The Winged Dragon of Ra's power and
toughness are equal to the amount of life
paid this way.
You may pay 5 life, destroy target creature.
Activate only as a Sorcery.