At the Land Of Dusk near the sell woman are some normal monsters. Every two to five minutes, there is a Goblin with a yellow hammer in is hand called "Hammer Goblin". Do not kill him; if he hits you ten times your head will become bigger, and you will become stronger for ten minutes.
In the first Tempskron map with all of the Hopies, there is a monster called Arma. They look like little armadillos. They will drop Mystic Crystals. It is possible to get up to twenty crystals in slightly over an hour.