March in, and claim that stuff as your own. If anyone gets in your way, acid puke them center of mass and/or turn them into clowns to serve you in battle.
dig a pit under the castle so it'll fall in, then climb in to the castle from the roof.
If all else fails, knock on the door using your grubby green hands.
Step closer and get ready to devour the face of anything that's on the other side of the door. Literately devour, you're putting those chompers to work.
bite the finger
Instead of pulling his finger, pull off his arm and eat it. A arm will have to do.
eat the door and escape
Continue through hatch.