After finding the Trident Zac doesnt know how to turn it on. He thinks it needs to be activated by Moon Light. After exploring her house Zac finds Ritas grotto and mermaid cave. After he swims in Lyla, Sirena and Nixie catch him. Just when they are about to battle the trident captures the moon light from Sirenas moon ring and it then charges up. Zac is free to unleash forces he cant control.
