The Leviathan

This subclass is 1 of a set of 4 being developed, one for each elder elemental as an optional patron of elemental power (including a rework of the phoenix already out there).  All aspects of my classes are somewhat derived from other spells or warlock abilities and should be quite balanced.  However, I'm open to suggestions.

You have bound yourself to an elder elemental known as Leviathan.  You feel the unstoppable force through you from elemental plane of water.  You might be quicker to take opportunities when they present themselves to crash in on your foes.  You feel an urge toward the chaotic nature of the sea, and understand the cleansing power of the water.  The Leviathan grants you power for the sole purpose of spreading its own influence.  For this reason, once the pact is formed there is little contact with your patron until you are powerful enough to perhaps summon its dreadful power to your own plane of existence.

Expanded Spell List

The Leviathan 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.

Leviathan Expanded Spells

Spell Level	Spells
1st	fog cloud, create or destroy water
2nd	alter self, lesser restoration
3rd	tidal wave, water breathing
4th	watery sphere, control water
5th	maelstrom, seeming

Bonus Cantrips

At 1st level, you learn the shape water cantrip.  It counts as a warlock cantrip for you, but it doesn't count against your number of cantrips known.

Slippery Nature

Starting at 1st level, your patron bestows upon you the ability to project yourself with fluid movement.  When an opponent moves within 5 feet of you, you may use your reaction to immediately move 5 feet per Charisma modifier without granting attacks of opportunity from it.

Watery Escape

Starting at 6th level, you can vanish in a splash of water in response to harm. When you take damage, you can use your reaction to dissolve into a puddle of water and move up to your speed.  You cannot be a target until you reform at the start of your next turn or until you attack or cast a spell at which point you reform from the water.

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

Watery Form

Beginning at 10th level, your patron teaches you how to shift your form into a liquid and back again.  You are able to transform yourself, along with everything you are wearing and carrying, into living liquid of a medium size and a shape of your own choosing.  While in this form you may move on ground or within water at your base movement speed.  You may enter and occupy the space of another creature.  You have resistance to non-magical damage and advantage on Strength, Dexterity, and Constitution saving throws.  You can pass through small holes, narrow openings, and even mere cracks without squeezing.  You are immune to grappled, paralyzed, petrified, poisoned, prone, restrained, and fall damage.  If you are in any of these conditions when you shift then you are freed from this condition.  

While in this form you are unable to speak, and any objects you were carrying or holding can't be dropped, used, or otherwise interacted with.  You are unable to attack or cast spells, but can attempt to grapple.  If you grapple a foe in this form they are grappled, restrained and may start suffocating.  You are immune to non-magical weapons.  You are vulnerable to cold damage, and if you take more than 1/4th of your life total in cold damage in this form you become partial frozen, reducing your speed to half.  If you take lethal damage from cold you become frozen solid, which has the same effects as being paralyzed.

This effect lasts 1 hour unless you dismiss it as an action to reform.  Once you use this feature you are not able to use it again until you finish a short or long rest.

Leviathan Summon

At 14th level you earn the right to summon forth the likeness of Leviathan itself to pummel your foes.  When you hit with an attack you can use your reaction to immediately summon a likeness of the Leviathan which crashes into your target and into the ground.  As the full force of Leviathan pushes through the target they will make a Strength saving throw or be pushed prone to the ground and stunned.  Regardless of the save they will take 5d10 bludgeon damage and 5d10 cold by the time the Leviathan has completely disappeared.

You must finish long rest before you can use this feature again.