The Enchantment Song is a song that when sang by a mermaid can make a land boy follow you around. It doesn't make mermaids able to control boys, but instead makes them follow them. It was used hundreds of years ago on sailors and sirens would sing their songs to sailors to crash them onto the rocks. This song is forbidden in the the girls' pod.
Lyla had a great plan to use the Enchantment Song on Zac. It was used on David by accident and he followed Nixie. David couldn't help staring, following, and pleasing Nixie. The enchantment was removed when Sirena blew into the particular shell.