Patronus Charm

Expecto Patronum

(Patronus Charm)

3rd-level conjuration

Casting time

Concentration, up to 1 minute

Range

Self

Components

 V,S

Duration

 instantaneous

Process 

You summon a spirit protector which appears in an unoccupied space next to you. The spirit appears to be angelic, fey or natural (your choice), but appears incorporeal none the less. The spirit disappears when the spell ends. If a enemy comes within 15 feet of you, the spirit will cause them harm for every turn they are in range. The enemy will suffer 3d8 radiant damage upon a failed Wisdom saving throw, or half upon a success.[1]

At Higher Levels 

The damage increases by 1d8 for each spell slot level used above 3rd.[2]

Harry Potter Spell Description

This charm is a defensive spell which will conjure a spirit-like incarnation of their positive emotions to defend against dark creatures; it can also send messages to other witches or wizards. It seems one’s Patronus will take the form of something important to the caster, and can change when one has undergone a period of heightened emotion.[3]

Etymology: Patronus means “protector” in Latin; in archaic Latin, it means “father”; considering the form Harry’s takes, this is interesting. The Latin word expecto means “I await”[4]