King Of Herrings

While your patron's mere existence is less deniable, few seem to have seen it directly. Some describe it as a kind of dragon or perhaps simply a cunning beast wishing to ascend to godhood. But swimming upstream is a challenge and it is willing to barter some power in exchange for your services.  They're as variable as the tides, and you may be surprised how they manifest when attempting to harness their power in unfamiliar waters.

How do you speak to your patron? Perhaps that's best left up a whispered dream. Do you nap by the docks, or a cottage overlooking a lake? Perhaps a glass of water on the nightstand during a good night's rest is enough. Beings of water are flexible, after all. As for your responsibilities, those might be flexible too. A feel-good goal of washing the corruption away from a defiled riverside community? Helping a circle of druids by the lakeside? Cutting down pirates and poachers rampaging along the coast? Depends how events flow...

Your patron's true name is unknown to you, and you suspect its fanciful title and occasional amusing manifestations are more a courtesy to you than anything...

Expanded Spell List

The River Serpent lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

River Serpent Expanded Spells

Spell Level	Spells
1st	fog cloud, create or destroy water
2nd	pass without trace, blur
3rd	sleet storm, water walk
4th	storm sphere, watery sphere
5th	maelstrom

Current Events

You learn the cantrips Thunderclap and Shape Water. You gain a swimming speed equal to your walking speed, and can hold your breath up to an hour.

When you are immersed in water or surrounded by bad weather (such as rain, snow, etc.) enemies have disadvantage in their Perception checks against you.  However,  your own checks in the same situations do not take disadvantage penalties.

You can distinguish whether a water source is potable by touch, though not the exact nature of its content.

 

Glacial Pace

Once per long rest, if you have taken the Lance of Lethargy invocation, you can have Eldrich Blast do cold damage instead but doubling its slowing effect.

Wet Wisdom

Your patron's more volatile side is revealed, warning you it brings mighty storms as well as serene deeps. Rather than fear, you admire its complexity.

At level 6, you gain half-proficiency in Insight if you didn't already have it. Also, when making a wisdom check, you can substitute your charisma instead. You can do this a number of times equal to your spellcasting modifier per long rest.

Scaling Defenses

At level 6, your connection to your patron strengthens, manifesting in shimmery scales. You gain resistance to cold damage and can add half your CHA modifier (rounded down, minimum one) when calculating your AC while wearing non-heavy armor.

Toxic Behavior

Despite its apparent serenity, your patron's anger manifests in subtler ways than just storms and waves. It can even slowly blight the same waters it attempts to maintain.

At level 10, you have become resistant to acid damage. Once per long rest you may use the Blight spell without slots or components.

 

Brine Imbibe

You can tolerate drinking (clean) seawater without deleterious effects.

Sonic Boom

Once per long rest, if you have taken the Repelling Blast invocation, you can choose for Eldritch Blast to do thunder damage instead, knocking an enemy up to Huge size prone.

Heavenly Serpent

At level 14, your patron's lofty dreams of controlling the very sky come to you.

You are immune to cold and thunder damage, and gain a flying speed equal to your walking speed. You can always tell which way is north.

Long Mist

Once per long rest, you can manifest a pleasant-smelling but eerie cloud of mist manifests 10 feet in diameter, centered on you for ten minutes. Any enemy entering that space must roll a Dexterity save on its turn or fall prone. Up to 5 allies (including yourself) gain the following benefits while in the mist:

• underwater breathing
• immunity to non-magical fire
• ranged weapon attacks and fire spells targeting them have disadvantage
• A single status effect from one ally (or yourself) can be removed at no cost.