Dartz, Yami Yugi and others in “Unfinished Business”

And so the Battle of Atlantis began! You see my father had opened up a gateway to the Dominion of the Beasts and he used the monsters within to form an army of his own.

Tell me, what was the battle's outcome?

Neither side were victorious and Atlantis sunk to the bottom of the sea. My father's monster army were scattered around the world and sealed away until they be needed again. The Leviathan was drained of its power and also sealed away. It's taken me 10,000 years to gather the energy necessary to bring it back. All that's left of me to do is to defeat you two in this duel. Then your souls will awaken the Great Leviathan and my plan will finally come to pass.

Hold on! We already defeated you! Our Master of Dragon Soldier should've wipe out the rest of your life points.

Perhaps it should have, but I'm afraid it didn't. Your pathetic attack failed short of its target. So this duel is still on.