The Dweller Below

You have made a pact with an ancient mysterious being from the depths of the world. They are not necessarily evil or good, but rather cloaked in mystery and work towards unknown goals. Your patron may be an aboleth or some similar creature for example, an ancient being whose knowledge and motives are beyond the comprehension of simple mortals such as yourself, or your patron could even be some minor god or arch-being.

Expanded Spell List

The Dweller Below 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.

Spell Level	Spells
1st	Bane,  Dissonant Whispers
2nd	Pass Without Trace, See Invisibility
3rd	Bestow Curse, Life Transference
4th	Evard's Black Tentacles, Summon Aberration
5th	Contagion, Modify Memory

Mark of the Dweller Below

Starting at 1st level you gain the ability to use your bonus action, to Mark a creature within 30 ft of you and the shadows around it begin to darken and coalesce. The target is marked for 1 minute, even if would have no effect after a certain point. All saving throws are made against your spell save DC. You may use this ability a number of times equal to your Wisdom modifier +1, minimum of once per long rest. Choose one of the following:

- Mark of the Helpless: The creature must make a Wisdom Saving throw, on a fail it gains vulnerability to force damage until the end of your next turn, at which point the Mark fades, on a success there is no effect.

- Mark of the Desperate: The creature must make a Wisdom Saving throw, on a fail the target must use its entire turn to move towards its nearest enemy and make a melee attack against it, until its next turn attacks against it are made with advantage. On a success the target takes psychic damage equal to your charisma modifier.

- Mark of the Impotent: The target must make a Wisdom saving throw, on a fail the target fails to the ground prone, clutching its head in agony. While prone the target may not stand up, move, or take actions or bonus actions. It may repeat the saving throw at the end of each of its turns and whenever it takes damage from a source other than this Mark. If the target failed the saving throw by 5 or more it takes 1d6 psychic damage at the end of each of its turns.

- Mark of the Fated: If the target is reduced to 0 hit points before the end of your next turn then it must make a Constitution  saving throw, on a fail the person who reduced the target to 0 hit points regains a number of hit points equal to half the damage dealt, rounded down. If the damage was the result of something other than a creature then you regain the hit points instead.

- Mark of the Feeble: The target must make a Constitution saving throw, on a fail the target's strength is reduced to 10, it has disadvantage on non-spell attacks and Constitution saving throws to maintain concentration on spells, and if it is wearing medium or heavy armor then its movement is halved.

Ire of the Dweller Below

Starting at 6th level, as a bonus action, you can remove a Mark or Hex from a Marked target within 30 ft to give your next attack against that target a -5 to hit but a +10 to damage or to negate the critical effect of an attack role made by the target.

Secrets of the Dweller Below

Starting at 10th level you gain proficiency in Intelligence based ability checks, if you are already proficient in any or all of them then you gain expertise in the ones you are proficient in. When you make a history check about a something of which your patron would be knowledgable about as determined by the DM (keep in mind that the Dweller Below is an ancient and mysterious entity and would have experienced quite a bit), you may expend a spell slot between first and fifth level to gain a bonus to your roll equal to 3 times the level of the spell.

In the Clutches of the Dweller Below

Starting at 14th level, as a bonus action you can cause gnarled hands formed from dark purple energy and shadows that have coalesced, or of some aesthetic fitting your patron (maybe vines sprout from the earth and form hands, or even tentacles or something) and grasp a creature within 30 ft of you.The target must make a Strength (Athletics) or Dexterity (Acrobatics) check agains your spell save DC, if the target is Marked by you then you may remove the Mark or a Hex to give the target disadvantage on the ability check. If the target fails then it is grappled, while grappled in this way the target is considered restrained. The target may use its action to repeat the saving throw, if it is marked or hexed by you you may use your reaction to remove the Mark or Hex, causing the target to fail automatically.