Luke cast the spell continuously because he hadn't found David's soul but when he did he cast the final part of the spell not too fast and not too slow or else he might mess it up.
A little magic circle formed on David's forehead and soon enough a bright golden light began gravitating from David to the gem on Luke's forehead.
David understood what was going on and tried to escape by attacking with a magic circle which was completely absorbed into the gem.
His skin slowly began to crack because he physically couldn't handle the power. When he had successfully absorbed about seventy-five percent he couldn't handle it anymore and he stopped, not before grabbing David and throwing him to the ground like he did to him earlier.
He then got down with all of his clones and they all slowly turned into dark gloopy poodles.
