Beast classification 

The three types of categories are

Beast

Being

Spirit

A beast is any creature that has sufficient intelligence to understand the laws of the magical community and to bear part of the responsibility in shaping those laws

a spirit is a special classification that was created for ghosts when they felt it was an insult to classify them as beings.

X: Boring

XX: Harmless

XXX: Competent Wizards Should Cope

XXXX: Dangerous/Specialist Training Required

XXXXX: Known Wizard Killer

Imps

Imps are known tricksters. They tend to stick to marshy areas, where it is easy to lure a target astray.

Bowtruckle

Bowtruckles are short, measuring no taller than eight inches, and are classified as XX. They are incredibly difficult to spot, since they essentially are tree creatures and their natural protection and defense system is to blend in with the tree in which they live.

Spell: The Knockback Jinx

Incantation: Flipendo (fli-PEN-doh)

Wand Movement: A downward diagonal to the right, followed by an upward diagonal movement to the right and ending with a swish

Concentration: Low

Willpower: Low to moderate