The movie I am trying to find starts in a house, in the country, with a hill that leads to a forest. There are 2 children, siblings, boy and girl, that run away into the forest. They meet a creature, either troll, goblin or leprechaun, who says he will help them but he is really bringing them to a witch. I think there was a doorway to another dimension/world where the witch is. At some point a band of Sprites show up and talk to the troll/goblin/leprechaun about kidnapping the children.