-CAUTION! BLOOD OF OLYMPUS REFERENCE BELOW!-

On Half-Blood Hill, Hazel was leading the Fifth Cohort into battle. She eventually came across an army of karpoi - grain spirits.

It was the easiest part of the battle. All Hazel had to do was yell 'SCHIST!!' The karpoi were so shocked they stopped advancing, and never noticed when the front rows of the Fifth turned them into multigrain cereal.

From The Blood of Olympus.