Muggles' Guide to Harry Potter/Magic/Oppugno

Overview
Oppugno apparently causes creatures to hate the target of the spell. The result is that the creatures influenced by the spell will attack its subject.

Extended Description
We only see this spell used once. Hermione, having seen Ron and Lavender locked in one of their embraces, has retreated to a disused classroom, where she has moodily created a flock of canaries which are circling her. Ron and Lavender, apparently seeking some privacy, also enter the classroom; Lavender quickly backs out, but Ron stays to exchange some words with Hermione. Hermione, angered, uses the spell to set the canaries on Ron as she is leaving.

There is mention later that Ron still bears the scars of the canary beaks and talons.

Analysis
It is uncertain whether this spell would work on any creature, or only on creatures that the caster has created. As we see this spell only the one time, we can only guess at its effects and applicability.

"Oppugno" in Latin translates directly to "attack".