The Parasite

Most Warlocks are bound by contract to their patron, be it a devil, a hag, or a lich. You, however, have found an intruder in your own body. This creature shouldn't be here, but you can't get rid of it.

This creature has imbued you with magical power which alters your physiology. The creature feeds off of chemicals produced by your body and as such needs to make you stronger so you survive. It may have a voice which only you can hear, or a voice which everyone can hear. 

Examples of Parasite Patrons include brainleeches used by Mind Flayers and Slaad, or even Symbiotes from Marvel Comics. 

Note: Some players may want their patron to control the character's body from time to time, with a mind of it's own. For these kinds of situations, other Warlock features could be used to represent this. For example, there is an Eldritch Invocation which relieves a Warlock if the need to sleep. This might be because their parasite takes over during the night. 

Expanded Spell List

The Parasite 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.

Fiend Expanded Spells

Spell Level	Spells
1st	inflict wounds, absorb elements
2nd	web, [spell]alter self[/spell]
3rd	haste, vampiric touch
4th	blight, black tentacles
5th	antilife shell, contagion

Two's Company

Starting at 1st level, your parasite begins to alter your physiology. This results in your body slowly adapting to feeding two mouthes, and protecting two minds. You gain 1 additional hit point, and you gain another additional hit point whenever you gain a level in this class. Additionally, you need to eat, drink and exercise twice as much as normal. You have advantage on saving throws against being charmed, and your thoughts cannot be read. 

Spontaneous Mutations

Starting at 6th level, your patron has begun to change your physiology even further in order to prime your body for the final transformation. You gain a pool of Mutation Points equal to your Warlock level x 5.

You may use these points to perform Spontaneous Mutations, techniques which temporarily alter your biology using magic. A full list of the Spontaneous Mutations availible to your character will be detailed at the end.

Any spent Mutation Points come back to you after a long rest. Many of your Spontaneous Mutation options become stronger once you reach 10th level. 

Hostile Takeover

Starting at 10th level, when you drop to 0 hit points, you can choose to stay conscious. If you do, you must still make your Death saving throws. Your character's mind becomes inactive, and the Parasite's personality takes over until your next long rest. Once you use this feature, you cannot use it again until your next long rest.

Note: Once the Parasite's personality has taken over, you may be asked by your Dungeon Master to relinquish control of your sheet. This is something you should talk to your Dungeon Master about in advance.

Total Symbiosis

Starting at 14th level, you can use your action to become an amalgam of you and your parasite for 5 minutes.

When you do this, you spend all of the points currently in your Mutation Points pool. Then, you gain the three following benefits for the next 5 minutes. 

• You regain 1d6 hit points at the beginning of each of your turns. 
• You add your Charisma bonus to all saving throws, in addition to any other modifiers. 
• Your size is considered Large.
• At the beginning of each of your turns, roll 1d4. You regain that level of spell slot. 
• You have a natural weapon, which you may choose in the next section.
• You gain an improved movement type, which you may choose in the next section.

Your natural weapon can be a bite, which deals 1d10 piercing damage, a pair of claws, which deal 1d6 slashing damage, or tendrils, which deal 1d8 bludgeoning damage, and have a range of 10 feet.

Your improved movement can be a +10 bonus to running speed, a swim speed equal to your running speed, or a climbing speed equal to your running speed.

When you use this feature, you cannot use it again for a week. 

Note: If you are not satisfied with the examples given for the Natural Weapons or Improved Movements, you and your Dungeon Master can choose an equivalent bonus, such as a flying speed, or grappling weapon.

Note: At this point in your Warlock's relationship with the patron, they may no longer be considered two different minds, maybe even using a single name or using plural pronouns. 

Spontaneous Mutations Options.

These are the Spontaneous Mutations your character can perform when they spend Mutation Points.

Psychotic Leap (15 Points): As a bonus action, the bones in your haunches and back shift. Until the end of your next turn, you have advantage on Strength (Athletics) checks you make to long jump, and the checks require no running start. Once you reach 10th level in this class, you also double your jump distance when you use this Mutation. 

Greater Sprint (5-10-15-20 Points): Your lungs swell like balloons, and your heart begins to pump rapidly. When you use this Mutation, you can spend either 5, 10, 15 or 20 points. Add that many feet to your movement until end of turn. Once you reach 10th level in this class, you may spend 25, 30 or 35 points on this Mutation, and running this way does not provoke attacks of opportunity. 

Muscle Memory (10 Points): As a bonus action, your mind goes blank for a moment as you engage the enemy. Next time you make a Strength check or Melee Weapon attack you are proficient in, you may instead of rolling, treat the result as 10 + your Strength modifier + your proficiency bonus.

Disjointed Limbs (15 Points): The bones in your arm become looser as your muscle relaxes. Until the end of your next turn, any melee attack you make now has the Reach property of 10 feet. 

Rapid Regrowth (25 Points): As an action, your body starts to produce cells thousandfold, attempting to patch wounds on your body. You may spend an amount of Hit Die up to your Charisma modifier (minimum 1), and regain the result. When you reach 10th level in this class, you may spend an additional 5 Mutation Points when you use this Spontaneous Mutation. If you do, you also regain an amount of hit points equal to your Warlock level.