Mantis Petra

"Lurks amongst foliage and attacks by flinging wind-scythes from a distance. They will harass you from afar, so get close and strike quickly. Their bodies are brittle and will easily fall to your nail."

Behaviour and Tactics
They hover just outside of the Knight's melee reach. They fling scythes at the player that will swoop down in a parabolic arc, slow at the apex, then come back up.

If possible, try to get slightly above them to lure them close and hit them with a Nail Art or Spell before they hover away again. Alternatively, using Howling Wraiths/Abyss Shriek or Grubberfly's Elegy will close the distance.

They often show up in groups with another Petra or a Mantis Traitor. Get rid of them first, as their aerial attacks make fighting ground-based enemies aggravating.

Dreamshield will destroy their scythes when making contact, making this charm useful against them.

Location
The Mantis Petra are very commonly found in Queen's Gardens, usually as a challenge in the platforming sections. Also found within the Colosseum of Fools, in the 9th, 14th and 17th wave of the Trial of the Fool.

Trivia

 * Strangely enough only the Mantis Petra marked by a red circle will respawn when reentering the room, all others will only respawn when the Knight rests at a bench.