Fangbeasts are the second Monsters encountered in Castle Story. The first Fangbeast to appear will trigger the Fangbeast Beatdown! quest. A new weapon, the Meat Cleaver, is required to fight a Fangbeast.
Note that Fangbeasts don't do anything to you or your stats. Like other monsters, the fangbeast simply deactivates a number of squares surrounding it: 5x5. You cannot access anything in those squares until the fangbeast is defeated. With 5 Health, Fangbeasts take between 3 and 5 hits to defeat.
Spawn sources: Animals (cows, chickens, pigs), Hot Pepper, Carrot, Trees, some Buildings (stable, hatchery, farmhouses), Fangbeast Trap (5 gems). Limited sources: Glimmeregg Bunny, Season 5 Training Dummy, Teacup Poodle, Shi Tzu, Ugly Goose.