The parasite

Your patron is a cosmic parasite, draining the vitality out of whole peoples and worlds. Upon forging a pact with such a patron, you become host to one of its nascent offspring. As you grow in power, the boundary between your identity and the parasitic larva within you blurs.

Spell Siphon

Your patron has taught you to siphon magic from your enemies and make it your own. When a creature you can see within 60 feet casts a spell of a level you can cast with your pact magic spell slots, you can use your reaction to force them to make a Charisma saving throw using your warlock spell save DC. On a failure, the spell is cast as normal and you siphon the knowledge of the spell. While the spell is siphoned, the creature cannot cast the spell again and you can cast it as if it was a warlock spell you know by spending a pact spell slot as normal. Once you cast it, the spell is no longer siphoned and you no longer know the spell. You can siphon a number of spells up to 1 + your Charisma modifier (minimum 1). If you exceed this maximum, a spell of your choice that you have previously siphoned is no longer siphoned. A spell is no longer siphoned if you go unconscious or die.

Physical Specimen

Starting at 1st level, your patron has enhanced your physical form to improve your utility as a host and pawn. When you finish a long rest, choose a number of the following benefits up to your Charisma modifier (minimum 1). You gain these benefits until your next long rest.
• Your maximum hit points increase by 1 for each level you have in this class.
• You gain darkvision out to a distance of 60 feet. If you already have darkvision, its range increases by 30 feet.
• Each of your movement speeds increase by 5.
• You have advantage on saving throws against disease and poison.
• Your jump distances are tripled and you gain a climb speed equal to your walking speed.
• When you make a Strength (Athletics) or Dexterity (Acrobatics) ability check you can use your reaction to add a bonus to the roll. This bonus is equal to your Charisma modifier.

Symbiotic Sentinel

Starting at 6th level, your patron remains alert to all threats to its host at all times. You cannot be surprised and you have advantage on Dexterity ability checks made to determine initiative. You also gain advantage on saving throws against being charmed and frightened.

Spawn Pawn

At 10th level, you learn the dominate person spell. It counts as a warlock spell for you, but it doesn’t count against the number of spells you know. You can also cast it once without a spell slot, and you regain the ability to do so when you finish a long rest. When you cast this spell, your patron enhances the magic, dealing psychic damage equal to your warlock level if the creature succeeds on a saving throw to end the spell. In addition, damage can’t break your concentration on this spell.

Larval Regeneration

Starting when you reach 14th level, when you die, a larval parasite bursts from your corpse the next turn on your initiative. You control the parasite, which disappears after 24 hours. The parasite is a Tiny creature, has an AC of 14, maximum hit points equal to half your maximum hit points, and a walking speed of 30 feet. It otherwise uses your statistics but cannot cast spells. As an action, the parasite can cause a creature within 5 feet of it to make a Strength or Dexterity saving throw (your choice) against your warlock spell save DC. On a failure, the parasite burrows into the creature dealing piercing damage equal to your warlock level. While burrowed inside a creature, the parasite cannot take any actions, cannot be targeted by attacks, and is immune to all damage except psychic damage. On each of the creature’s subsequent turns it can use its action to make a Constitution saving throw against your warlock spell save DC. If the creature succeeds, the parasite is ejected from its body and into an unoccupied space of the creature’s choice within 5 feet of it. If the parasite is still burrowed inside the creature when its turn ends, the creature takes necrotic damage equal to twice your warlock level. If this damage reduces the creature to 0 hit points, it immediately dies, the parasite disappears, and you take over the body of the humanoid as if you had been targeted by the reincarnate spell and rolled the race the humanoid had been. If you are returned to life, such as by the revivify spell, your parasite immediately disappears. Once you use this feature, you can’t use it again until you finish a long rest.