The Swarm

Those who forge a pact with the Swarm become conduits for this collective wisdom, embracing the strength of unity and sheer numbers. They can tap into the minds of their fellow Swarm members, sharing insights and strategies instantaneously. Through this telepathic connection, the Swarm Warlock and their allies are able to coordinate their actions with uncanny precision, their thoughts interwoven into a symphony of calculated movements.

Expanded Spell List

The Swarm 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	find familiar, speak with animals
2nd	suggestion, augury
3rd	fireball, bestow curse
4th	locate creature, wall of fire
5th	dominate person, insect plague

Rapport Swarm

As an action, you can extend your swarm's presence in a 20-foot radius. Your swarm's influence can go around corners and affect only creatures with an intelligence of 2 or higher that aren't constructs. Affected creatures can communicate telepathically with one another while they are within 30 feet of each other. The effect lasts for 1 hour. 

Synthesis

Starting at level 1, you are lent the power to command your own swarm. When a creature is in your swarm, you may expend a Synthesis Point to empower any of your swarm abilities. You start off knowing three such features: Append, Puppetry, and Swarm Sight . You learn more swarm features as you gain levels in this subclass.

When you spend a synthesis point, it is unavailable until dawn of the next day, at which your swarm's power is restored and all your synthesis points are restored. You do not need to sleep in order for your swarm's synthesis to recharge.

Some of your swarm features require your target to make a saving throw to resist the feature’s effects. The saving throw DC is calculated as follows:

Swarm save DC = 8 + your proficiency bonus + your Charisma modifier

Append
As an action, you may expend 1 Synthesis Point to add a willing creature with an intelligence less that or equal to double your proficiency bonus to your swarm's influence. You may have a number of creatures in your swarm equal to your warlock level.

Puppetry
You can spend 1 Synthesis Point use your bonus action to command a creature in your swarm to use one of their abilities. The creature commanded must be able to use that ability and any charges are expended upon use.

Swarm Sight
You are able to peer through the eyes of a swarm member for 1 minute. Expend 1 Synthesis Point to glance through the eyes of a creature in your swarm as an action.

Swarmmeld

Starting at 6th level, you can expend 2 synthesis points to call upon your swarm to lend you their essence. When you do this, you are able to gain a racial trait or feature from a creature in your swarm that you can see. The trait gained will last for only 1 minute.

Once you use this feature, you cannot use it again on the same creature until dawn of the following day.

Symbiotic Bond

Starting at 10th level,  you can expend 4 synthesis points as a bonus action to add damage dealt to your swarm to your temporary hit points. When a creature in your swarm drops to 0 hit points, it cannot be revived, however, the attacker is dealt necrotic damage equal to your Warlock level. This effect ends and at the start of your next turn.

Song of the Swarm

Starting at 14th level, you can spend and minute to expend 7 synthesis points to command your swarm to begin singing an enchanting tune, any creature that can hear your song must make a wisdom saving throw. Any creatures that fail the save and meet your swarm's requirements are added to your swarm, ignoring your swarm creature maximum, for the next 24 hours.

While an affected creature is part of your swarm, you cannot command it to do anything that would cause it to injure itself or anyone it considers to be a friend or else it will leave your swarm and the effects of the failed save come to an end.