One creature with a swim speed that Dagon can see within 120 feet of it hears the telepathic commands of Dagon and must make a DC 21 Wisdom saving throw. On a failed save, the creature is charmed for 24 hours. While charmed, it must follow the orders of Dagon to the best of the target's ability and it is immune to being charmed or frightened by another effect or spell. A target can repeat the saving throw when it takes damage, ending the effect on a success.