You need some kind of crystal. I can't remember what color though. You also need to get the golden feathers i think. I'm not 100% sure on any of this so please don't critisize me!

Are you talking about the cemetary or getting into the castle realm?

if its the castle realm you need 125 purple crystals and twelve snake fangs i played the
first level in the mountain realm til i had enough and also in the first level in castle
realms after you play it enough you are able to attempt to unlock a new charecter! hope
thet helps bye!

Um, i'm pretty sure they're talking about after you get the 28 golden fangs guys. I'm
stuck there too

Beat Skorne the second time. Then the 3rd level opens and u can go find the 13th runestone
as well