During one of your many adventures across the world you come across a strange extraplanar entity. Upon contacting the entity, it reacts immediately and engulfs your arm, however it does not seem to be making any attempt to harm you. Instead, the creature seems to become part of you and eventually you learn to wield it as a weapon. It can take various forms and even the form of ranged weapons too as it shifts and molds itself around you. Despite its initially harmless bonding to you, it feels as if the creature is slowly draining you. You may also begin to hear the voice of a being originating in some distant corner of the universe, into the far realm.

Level 3: Level 3: Entity Awakens

The entity that is attached to your arm awakens and you can use an action to will it to take the form of any weapon in which you are proficient in. You may also choose up to 3 weapons to gain mastery in. For any weapon that the entity takes the form of you can use either its normal attack modifier (strength/dexterity) or you can use your constitution modifier instead. You can still be disarmed but instead of dropping your weapon, the entity recoils back into itself and becomes dormant for however long you would be disarmed for. However, you can brute force the entity back into action, causing it to absorb your very essence to fuel itself. As a reaction you can deal 1D4 psychic damage to yourself and the weapon will immediately reform on your arm.

Level 3: Level 3: Lifeforce Leach

The entity must feed on something regularly or it may turn to its wielder for sustenance. Every 12 hours the entity must be used to harm and/or kill another creature, otherwise it will deal 1D4 psychic damage to the wielder. During combat, after you land a killing blow or critical hit, the Entity will leach of the targets life force and imbue your next attack with an additional 1D6+Con psychic damage. You can also willingly take 1D4 psychic damage and charge the weapon with the thirst for more pain, giving your next attack advantage to hit (no action required). You can do this action a number of times equal to your constitution modifier, refreshing on a short or long rest.

Level 7: Level 7: Evolved Entity

You have killed many creatures and absorbed their life force leading the entity to evolve. Upon reaching level 7 the entity now has the ability to convert the damage type of whatever weapon it takes the shape of.  The weapon can either keep its regular damage type (slashing/piercing/bludgeoning) or it can instead deal necrotic or psychic. You must take a long rest to change the damage type of the weapon as your mind subconsciously wills the entity to change itself over the duration.

Level 10: Level 10: Growing Symbiosis

You have grown a stronger bond with the entity, becoming comfortable with it taking your lifeforce for mutual gain. As a bonus action you can allow the entity to engorge on your life to charge a powerful strike. You take 1D4 psychic damage and you can choose one of the following benefits for your next attack:

1. The attack deals an additional 2D6 + con modifier damage, matching the damage type of the weapon. If this attack is a critical hit or it kills the creature, you can immediately regain the health spent to make it.
2. As you make the attack roll the weapon lashes out to an additional enemy. Make another attack roll against the closest enemy within 30ft, other than the one targeted by the initial attack. The enemy who gets hit by the second attack suffers 1D6+Con in weapon damage and must make a constitution saving throw (DC 8 + attack modifier + proficiency bonus). On a failure the creature gets wrapped in a fleshy tendril and flung towards the initial creature, causing them both to take bludgeoning damage equal to your constitution modifier.
3. Your next attack gains a bonus to hit which is equal to the psychic damage you took to cast this. On hit, the entity absorbs the creature's life force and redirects it to you, healing you for 2D6 + constitution modifier hit points. If the attack misses you gain none of the healing.

Level 15: Level 15: Far-land tides

Whenever you are hit by an attack or spell and the attacking creature has line of sight on you, you can make a reaction to flood their mind with extraplanar horrors. The creature must make a wisdom saving throw (DC 8 + constitution modifier + proficiency bonus) or become frightened. They also take 2D6 psychic damage or half as much on a successful save.

Level 18: Level 18: Enlightened Entity

Once per long rest, you can give in to the entity and fully embrace its malice. For 1 hour you gain the following benefits and you can choose to end the effects early.

• You gain advantage to all intelligence/wisdom/charisma saving throws
• Your attacks deal an additional 1D6 psychic damage in addition to any other bonuses
• You are resistant to psychic damage
• You can sacrifice all your movement on a turn to blink to a target within 60ft
• Once during this hour you can use an action to unleash tendrils in every direction within a 30ft radius. Every creature within this area makes a constitution saving throw (DC 8 + constitution modifier + proficiency bonus). On failure they are pulled towards you and suffer 2D6 of your weapons current damage type and in addition you heal 1D4+Con hit points for each enemy pulled.