Take sheaf of wheat. It becomes animated and takes off. Go S to farmhouse. The animated scarecrow turns up and the farmer chases him away, leaving opening to cellar unguarded. Take another horseshoe.
Sandwich potion is now ready.
To activate, fill flask and click on Zanthia. It turns into a magnet. Replace bowl and remove it, making dragon cry. Collect tears in empty flask. Click sandwich on guards.