Soul Blade

You can only put Soul Blade onto the battlefield if you control Annihilation Dragon.
During your opponent's turn, Soul Blade isn't a creature.
If a source would inflict damage to an Annihilation Dragon you control, prevent all but 1 of that damage.
When a creature, except a legendary Shadow artifact creature, enters your battlefield, increase this card's power and toughness by the mana value of that creature then sacrifice that creature.