A constant spell affects the monster without the monster needing to cast it, and its duration is unlimited. If a constant spell gets counteracted, the monster can reactivate it by spending the normal spellcasting actions the spell requires.
AC 24; Fort +12, Ref +15, Will +18
HP 90
Drowning Melody(auditory, occult)
Trigger The merfolk or a creature under the effect of their Storm Song within 60 feet is targeted by a spell or auditory effect
Effect The merfolk sings a warbling tune reminiscent of a drowning creature. They attempt a Performance check to counteract the triggering spell or effect. The merfolk can't use this ability again for 1d4 rounds.
The merfolk sings a discordant tune that buffets the senses like a raging thunderstorm. Non-merfolk creatures in a 120-foot emanation must attempt a DC 25 Will save or become Confused for 1 round. The creature can't target merfolk while confused in this way. If the merfolk uses this ability again on subsequent rounds, they extend the duration by 1 round for all affected creatures. Once a creature succeeds at any save against Storm Song, that creature is temporarily immune to Storm Song for 24 hours.