CHA, +10 attack, DC 18
The Song of The Piper. The Piper comes to all as a herald of the end. The Piper can choose to mark any creature who hears their song, regardless if the creature is capable of hearing. Any creature marked by The Piper who hears their song has to make a DC 20 WIS Saving Throw or be frightened until the next dawn or until an ally of the affected creature who also isn't affected themselves spends 1 hour calming the affected creature down. Those who laugh in the face of death have a DC 15 WIS Saving Throw as their pride blinds them of the purpose of The Piper and its song. Additionally, The Piper gets advantage on attacks and +5 damage against creatures frightened in this way.
Multiattack. The Piper makes 3 attacks, only one of which can be a Sonic Attack. Sonic Attack. The Piper uses its trumpet to create a high-pitched screeching sound to deal 2d6 Psychic Damage to creatures withing 15 feet of it. Creatures affected by this must make a DC 18 CON Saving Throw or be paralyzed until the end of The Pipers next turn. Additionally, if The Piper chooses to use this attack, it has to be the first attack used in that turn. Firebolt. The Piper can choose to cast the cantrip Firebolt as part of its attack action. Pebble. The piper chucks a pebble at a target. On a hit , the attack deals 1d4 magical bludgeoning damage and a d100 is rolled , on a 1-20, the target is stunned until the end of the targets next turn. On a 21-100 nothing happens.
Legendary Resistance (1/Day). If The Piper fails a saving throw, it can choose to succeed instead.
The Piper can take 1 legendary action. Only one legendary action can be used at a time and only at the end of another creature's turn. The Piper regains spent legendary actions at the start of its turn. Resilient Adaptation. The Piper will randomly change one of its temporary resistances/immunities to another random one. If a resistance changes to another resistance it already has, it becomes an immunity. An immunity can be changed into a resistance of the type it is and another random damage type.
Any time, any place, as long as someone doesn't value life around them or their own, a Piper stalks their prey. A piper stalks only one target and a target can only be stalked by one Piper at a time.