Board Thread:General Discussion/@comment-31981697-20170722123329/@comment-13682699-20170723051625

If he absorbed the determination SOUL, then he would have the power equivalent of a human SOUL with the determination trait. His magic would be much stronger and no single human would be able to overcome his determination (since he has injected determination from various human SOULs on top of a determination SOUL) so he could SLR freely. At this point he would either kill Asgore or Toriel(or both), take their monster SOULs, and venture through the barrier where he could then freely use his power on the surface. Whether or not anyone could stop him at that point is indeterminate.