Magister Winonin:
In order to upgrade a Level 13 Soul Crystal to a Level 14 Soul Crystal, you must defeat either Valakas, Antharas, Scarlet von Halisha or Balor, all of which possess strong souls. It is more difficult to absorb the soul of Balor than that of Valakas, Antharas or Scarlet von Halisha. It can also easily become a Cursed Soul Crystal, I'm afraid.
In fact...
"What?"