Blood of the Siren

Your bloodline descends from those who live their lives beneath the waves of the world, using their hypnotic voices and charms to lure victims into a watery grave. As a siren, you might have been destined to join your brethren in becoming the scourge of all who travel the seas, but your ancestor broke free from this way of life and sought a new path, perhaps they were banished for some great offence in their past, or maybe it was your very birth with another race that saw you either hidden or abandoned. You could be the first of this bloodline, or perhaps you are a long forgotten descendant, but this bloodline has defined you ever since you could remember.

Aquatic Adaptation

When you take this class at first level, you are capable of shifting between your mortal land-walking form and that of your siren bloodline. When you are submerged in water, your lower half resembles that of an aquatic creature (your choice) and you gain a swimming speed double that of your walking speed, the ability to breathe underwater and the ability of darkvision out to a distance of 120 feet whilst underwater.

Siren Song

Starting at 3rd level, you can charge your performance with your hypnotic voice.

Your voice can serve as a hypnotic beacon that can enthral and charm those that hear it, singing for 1 minute you can attempt to put them under your spell. After one minute of singing, choose a number of humanoids within 60 feet of you who watched and listened to all of it, up to a number equal to your Charisma modifier (minimum of one). Each target must succeed on a Wisdom saving throw against your spell save DC or be charmed by you. While charmed in this way, the target idolizes you, it speaks glowingly of you to anyone who talks to it, and it hinders anyone who opposes you, although it avoids violence unless it was already inclined to fight on your behalf. This effect ends on a target after 1 hour, if it takes any damage, if you attack it, or if it witnesses you attacking or damaging any of its allies.

If a target succeeds on its saving throw, the target has no hint that you tried to charm it.

You can use this feature once, plus a number of times equal to your charisma modifier.

The Song of the Storm

At 6th level, you gain the ability to subtly control the weather around you.

If it is raining, you can use an action to cause the rain to stop falling in a 20-foot-radius sphere centered on you. You can end this effect as a bonus action.

If it is windy, you can use a bonus action each round to choose the direction that the wind blows in a 100-foot-radius sphere centered on you. The wind blows in that direction until the end of your next turn. This feature doesn’t alter the speed of the wind.

Discordant Wail

Starting at 6th level, you have learned how to channel your normally harmonious voice into a destructive wave of energy.

Harnessing the vengeful and hateful side of your ancestral heritage, you can cause agony and distraction in your enemies. Choose a number of creatures within 60 feet of you, up to a number equal to your Charisma modifier (minimum of one). Each target must succeed on a Wisdom saving throw against your spell save DC or take 5d6 psychic damage, losing concentration on spell or on any task that required concentration automatically and they have disadvantage on either the next saving throw or attack roll they make, whichever comes first in the next minute.

The target automatically succeeds on the saving throw if they can't hear. If they succeed on their saving throw, they take half damage but suffer no other effects

You can use this a number of times equal to your Charisma modifier (minimum of once).

Cold Blooded

At 14th level,your hit point maximum increases by 1 and increases by 1 again whenever you gain a level in this class. Additionally, when you aren’t wearing armor, your AC equals 13 + your Dexterity modifier. Additionally, you are able to make use of your adaptations even when not submerged in water, and every attack roll you make whilst in water now has advantage. You alignment also changes if it was good it now shifts to either neutral or evil, your choice.

Abyssal Undertow

Starting at 18th level, when a creature is held under any magical effect that affects their mind or has taken psychic damage this turn, you can use this feature to drag their mind into the dark abyss of their own mind, becoming immobile for one turn, but immune to all damage and effects. They are mentally transported by your voice into an underwater landscape, where they are subject to all the horrors and nightmares you wish to inflict upon them.

At the end of your next turn, the target regains all of its senses, but begins coughing up salt water as if they had been drowning. At the end of your next turn, they automatically regain their senses, taking 10d10 psychic damage and, unless they can beathe underwater 5d10 cold damage as they attempt to recover from their horrific ordeal. Because of the horrors you have inflicted on you, they have disadvantage on attacks against you and on saving throws against your spells for the next minute.

Once you use this feature, you can’t use it again until you finish a long rest.