In the bonus map, Fangorn Forest, the first level contains a portal. Go north-east almost up to the end of the level where your pointer will register red. Turn left and walk up to a space in the grass with a tree stump next to it. Stand next to the space and you will be transpoted back near the begining. You can go back and forth between these two and orcs and goblins will reapear every time, making for easy experience.