Honestly? Oramus shouldn’t have a Charmset. Neither should Cytherea or Sachaverell.
Sometimes some ideas that make cool setting fluff are not things PCs should have access to, not just because they lack mechanical balance but because the very idea of mechanizing them would lessen them.
Oramus is the dragon beyond the world. He is the part of the map that is unexplored and unexplorable. He is why “here be dragons” is a warning. You don’t get to travel into the Beyond or view the Things That Can Not And Must Not Be. You don’t get to know Cytherea. You don’t get to be Contessa, even if your Path might be something you don’t want.
Sometimes things aren’t meant for PCs and that’s perfectly fine. Sometimes things really are better if they remain a mystery. Considering all three of the above Yozi can be safely and roundly ignored in every single game that is ever played… I don’t feel the need to pull back the curtain.