Winged God Dragon of Ra

Sacrifice three creatures in order to cast this card.
This cards power and toughness are the total
power and toughness of the sacrificed creatures.
God Dragon cannot be countered or sacrificed.
Control of God Dragon cannot change.
Shroud from non-God creatures.
Sacrifice God Dragon at the beginning
of the end step if it wasn't cast.
Pay all but one life: Put that many
+1/+1 counters on God Dragon.
Pay 3 life: Destroy target creature.