Leviathan

Extended Spell list

1st- Command, Sleep
2nd- See Invisibility, Detect Thoughts
3rd- Tongues, Water Breathing
4th- Black Tentacles, Control Water
5th- Mislead, Legend Lore

Leviathans Echo

 

At level 1, once per short rest you can call on the Leviathan's knowledge to get advantage on your next arcana, history, or religion check.  Additionally, you can use the voice of the Leviathan to send out a psychic shock wave around you in a 15 foot circle.  All creatures within range must make a wisdom save against your spell save DC.  On a fail, they take 1d6 psychic damage, and half as much if they pass.  You can use this equal to your charisma modifier.  You regain half uses on a short rest, and all uses on a long rest.

At higher levels: This deals 2d6 psychic damage at level 5, 3d6 at level 11, and 4d6 at level 17.

Insight Nature

 

At 6th level, you can probe deep into the desires of other creatures an equal amount of times per day to your Charisma modifier. Roll a spell attack using Charisma, and on a 15 or above, you learn their deepest desires. From 7-14, you learn only their surface level desires of that moment. Otherwise, it simply fails. You may use this ability only once per long rest on the same creature.

Whispering Depths

 

At 10th level, you gain further abilities tying you closer to your patron:

• You gain the ability to breathe underwater and a swim speed equal to your walking speed, additionally you may communicate with fish and other aquatic life.
• You can communicate telepathically with creatures that have a shared language and that you can see within 120 feet.  They can communicate back if they wish to.
• You no longer sleep, you now go into a trance and only need to sleep for 4 hours.  

Knowledge Drain

 

At 14th level, as an action, you can attack the very minds of your enemies. Make a spell attack roll against an enemy you can see. A hit causes them to take 4d6 damage and they also lose their reaction until their next turn. If the creature dies from the damage of this ability, you gain hit points equal to the damage done by this ability, and you gain all knowledge this creature possessed as if it was from your own memory.