The dragon's Immortal is more powerful than his Invincible One. He hates to admit it, but the concrete evidence is right in front of him. That is the reason why the Dark Ancient Dragon is still flapping its wings.
His Plunder unique skill could actually steal its skill, but he would have to kill the dragon first, which is currently impossible as long as the dragon possessed the Immortal unique skill.
There is actually an effective way that guarantees results, but Raphael absolutely does not want to do it. The dragon is not after all like his two beloved mothers.
Speaking of the devil, getting rid of its Immortal unique skill is skillfully possible with the available resources he has. For example, the Despoil ability of his Mother's legendary weapon, but only his Mother could utilize that ability.
