Swarm Commander

While some rangers have sought out the companion of the beasts of land, sea, and air, forging strong bonds with them to triumph over adversity, you have chosen instead to exert your will over entire swarms of smaller creatures and use them to control the battlefield around you. Opting for quantity over quality, these creatures are more suited for confounding an enemy’s effectiveness than posing a threatening fighting force. By posing as the commander to these disposable beasts, you are capable of creating complications for your opposition and shaping confrontations to your designs.

Ranger's Minions

At 3rd level, you have gained the fundamental understanding to bring a swarm of like creatures under your direct command. Create your swarm by selecting a Beast creature that is no larger than Tiny. Your swarm has the statistics of that creature with the following changes:

• Has hit points equal to 5 + 3 times your Ranger level
• It adds your proficiency bonus to its AC
• Its attack rolls are increased by 2 + your proficiency bonus and it deals 1d6 + your proficiency bonus damage on a hit. If the swarm has half its hit points or more, it deals an additional damage die.
• It has resistance to bludgeoning, piercing, and slashing damage and is immune to being charmed, frightened, grappled, paralyzed, petrified, prone, restrained, or stunned
• The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny creature. The swarm can't regain hit points or gain temporary hit points.
• The space that a swarm occupies counts as difficult terrain to creatures that are hostile to it.

Your swarms are ever at your beck and call. During your turn, you may summon swarms to unoccupied spaces you can see within 20 feet of you, appearing either from the surrounding area or from somewhere on your person.

You control a number of swarms equal to your proficiency bonus. When you summon one, you choose whether it is one that you have already summoned or one you haven’t. If a swarm’s hit points fall to 0, it can no longer be called by you. All of your swarms recover their lost hit points when you complete a long rest, but cannot recover hit points in any other way.

In combat, your swarms act during your turn. Each can move and use its reaction on its own, but the only action it takes is the Dodge action, unless you take a bonus action on your turn to command one of your swarms to take another action. That action can be one in its stat block or some other action. You can also sacrifice one of your attacks when you take the Attack action to command the swarm to take the Attack action. If you are incapacitated, the swarm can take any action of its choice, not just Dodge. Following combat, you choose if your swarms linger or if they scurry away to hide themselves. If you die, your swarms abandon the battlefield in self-preservation; these swarms retain their current hit points when next they are summoned.

Summon Lieutenant

Starting at 3rd level, you gain the ability to summon a creature to act as your lieutenant. You learn the find familiar spell, which counts as a ranger spell for you. You may expend one of your swarm summons in place of a spell slot to cast this spell as a ritual. Your familiar takes the form of the same creature type as your swarm.

Pack Tactics

Starting at 7th level, you have better learned how to organize your swarms to work together on the battlefield. Your swarm has advantage on an attack roll against a creature if at least one of the its allies is within 5 ft. of the creature and the ally isn't incapacitated.

Additionally, if one of your swarms moves into the space of another of your swarms, and both have fewer than half of their maximum hit points remaining, you may combine them into a single swarm that has hit points equal to the remaining hit points of both.

Ankle Biters

Starting at 11th level, your swarms are particularly voracious. The swarm can make a melee attack against a creature that moves more than 5ft while within its reach.

Inexorable

Starting at 15th level, your swarms become adept at harassing their targets. If your swarm hits with an opportunity attack, they may immediately move 5 feet toward the creature they hit.