Exactly what it says on the tin, give your spell a name and describe it's effects. Be as original, or unoriginal, as you want.
Mine
Name: "Ni!"
Description: In short, sharp pronunciations causes both fear and irritation to build in the target. Frequent use of 'Ni' will eventually cause target to go insane and start hallucinating about shrubberies. Shouting 'NI' will cause the target's head to explode, followed by a shrubbery growing out of the neck.
Mine
Name: "Ni!"
Description: In short, sharp pronunciations causes both fear and irritation to build in the target. Frequent use of 'Ni' will eventually cause target to go insane and start hallucinating about shrubberies. Shouting 'NI' will cause the target's head to explode, followed by a shrubbery growing out of the neck.