This has enemies that are way too strong even early on and take a lot of time. It does start to get a little boring after a while due to it being repetitive.
Tanky enemies with maxed out defense (Such as the Riverfish) need Magic Damage or Damage over Time to effectively kill.
Magic Damage does a specified amount of damage, bypassing defense entirely, and allowing you to kill these tanky enemies.
As the character in the Tutorial house puts it "If something's barely taking any damage, try hurling some spells at it!"