after giving the frog with the reed, all he says is "the deed has been done" but doesnt give you a crown. and the witch says to do come back with what she wants. theres nothing else to interact with so what are you supposed do to?
Glad you asked! ^^ After interacting with the frog you must go to the underground and interact with the dead lizard queen to obtain the crown. You reach the underground by climbing the vines to the right. Hope I helped!
