Manic

According to Sepulcher8:

"Manic will always move your champion counter-clockwise (to the right if it's underneath the nearest opposing champion, and to the left if it's above the opposing champion) until it lines up in a straight diagonal line with that champion."

For 2x2 champions, Baskitkase explains:

"Use the top left square for both manic champ and target. Obviously the top left and top left will not touch, but you'll need to make contact (for melee or get in range for ranged manic) for the manic to complete."

(Also, note Manic is a nonbasic attack)