They mess with him

Between the chopping of wood, the pounding of blood in his ears, and his own internally muttered curses at his employer, Jack couldn't hear the chittering and giggling of the technicolor trouble makers swiftly approaching. In addition, his tunnel vision and focus on his task kept him from looking over his shoulder and catching any of the five little blips of light darting in and out of the grass behind him. No, he had no idea what was in store for him...

To be fair, neither did the pixies. Chaotic little things by nature, they only knew what they wanted to do, not how they would do it or what the exact result would be. In fact, only one of the Fay mischief makers managed to cast the first spell. To the surprise of Jack and four of the pixies (and the delight of the latter)...