Fall to Die Damage

When "Fall to Die Damage" is placed on the stack,
the spell caster must choose a creature an opponent controls.
Then roll a D-20.
1-9: The selected creature deals damage equal to
its' power to the caster of "Fall to Die Damage"
10-19: The selected creature deals damage equal
to its' power to it's owner
20: The selected creature gains double strike,
attacks its' owner,
then goes directly to the graveyard.