Rat King

Rat Kings are those who are cast aside by society, and who find companionship in the plague-carrying rodents of the holes of refuse in the world. Perhaps you found yourself in the sewers after being orphaned, or perhaps your parents gave you up to the wilds, because they couldn't afford to keep you. Or maybe you left of your own accord, found a ship, stowed away, and befriended the rats of that ship with gifts of food and shelter... 

Whatever the cause, you have found yourself to possess supernatural abilities, reminiscent of Rats, you have sharper teeth, longer fur, and can influence rodents you meet more easily. In addition, you have a swarm of mystical rats bonded to you which you can call upon to aid you. Men might shun you, but that no longer matters, for you have your pack with you.... and your pack is all that you need...

Sometimes a Rat King might be found living in the sewers of a large city, as a sort of urban legend who the impoverished of the city turn to when all other options have been exhausted. Some of these urban legends even have basis in fact, a Rat King might help people who come to them for help, there is much to be found in the deep places of the world after all... for those who know where to look.

Other times, a Rat King might stride the countryside in secret, stealing and taking whatever they can, whatever strikes their fancy, and whatever might improve them and their pack's chances of survival. They might prefer to stay unseen, so as to not incur the wrath of guards or commonfolk, or they might simply slay everyone in their way, few can stand against the ominous tide of vermin.

Rat Kings might even find themselves advisors, spymasters, working in high positions that suit their talents, though still unnerving all who see them. Sometimes people need spies, or information, or people to keep secrets and to advise them without any sycophantism. Rats tell their secrets to no-one, so they are perfect for that.

Gift of Rats

3rd-level Rat King feature

Your front-most teeth elongate like those of a massive Rat, and wounds your bites inflict typically become quickly infected. It is a natural weapon, it counts as a simple melee weapon for you and you add your Dexterity modifier to the attack and damage rolls instead of your Strength Modifier. It deals 1d6 piercing damage on a hit.

Once on each of your turns when you damage a creature with this bite, you can attempt to channel the magic of Rats through the bite, and the target of that attack must make a Constitution Saving Throw against your Ranger Spell Save DC or suffer 1d6 Poison Damage and become Poisoned until the end of your next turn. This damage increases to 1d8 at 11th level.

Swarm of Rats

3rd-level Rat King feature

A pack of magically sustained rats have bonded with you. The swarm is friendly to you and your companions, and it obeys your commands. See this creature’s game statistics in the Summoned Rat Swarm stat block, which uses your proficiency bonus (PB) in several places. You determine the swarm's appearance; your choice has no effect on its game statistics.

You can magically summon the swarm bound to you. As an action, you can summon the swarm, which appears in an unoccupied space of your choice that you can see within 30 feet of you.

In combat, the Summoned Rat Swarm shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take another action. That action can be one in its stat block or some other action. If you are incapacitated, the Summoned Rat Swarm can take any action of its choice, not just Dodge.

Once you summon the Summoned Rat Swarm, you can’t do so again until you finish a long rest, unless you expend a spell slot of 1st level or higher to summon it.

The Summoned Rat Swarm remains for a number of hours equal to your proficiency bonus, until it is reduced to 0 hit points, until you use this feature to summon the swarm again, or until you die. Anything the swarm was carrying is left behind when the swarm vanishes.

Vermin Speech

3rd level Rat King feature

You manifest features that make you appear more rat-like, such as longer fur all over your body, looking more emaciated and wild, fingernails lengthening, even perhaps a Rat's tail. You have advantage on Wisdom (Animal Handling) checks made to influence small or tiny beasts, and you can communicate simple ideas with any Rat(s) using a language that is a series of clicks, squeaks, chirps and whistles that is only understandable by you and other Rats.

Opportunistic Survivor

7th level Rat King feature

Rats typically find themselves living in places like sewers where the meat is never fresh, and the water is always full to bursting with germs and diseases, naturally, you have adapted to this, to better survive using whatever resources you can find.

You and your Summoned Rat Swarm both gain resistance to Poison Damage and you both have advantage on any saving throw made to avoid the Poisoned condition or end the Poisoned condition on yourselves. You are both immune to disease as well.

In addition, the Summoned Rat Swarm's attacks deal an additional 1d6 Poison Damage, and they now count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Fury of the Downtrodden

11th level Rat King feature

Your spiritual bond between you and your rats has deepened significantly. You gain one of the following features of your choice to reflect your deepening bond.

Cursed Rat Form

Your body changes even more, becoming far more Rat-like, hair growing even thicker, body shape changing somewhat to a hybrid between your former appearance and that of a giant rat. 

You gain the following abilities.

Shapechanger. You can cast the Polymorph spell without expending a spell slot. When you cast the spell this way, you do not need to provide material components, you can target only yourself and can only transform into a Giant Rat.

Once you cast the Polymorph spell in this way, you can't do so again until you finish a short or long rest

Keen Smell. You have advantage on Wisdom (Perception) checks that rely on smell.

Pack Tactics. You have advantage on an attack roll against a creature if your Summoned Rat Swarm is within 5 feet of the creature and the Summoned Rat Swarm isn't Incapacitated.

Flurry of Bites

Your Summoned Rat Swarm increases in size from a medium swarm of tiny beasts to a large swarm of tiny beasts. It gains a bonus to its maximum hit points equal to your Ranger level.

Whenever your Summoned Rat Swarm takes the Attack on its turn, it can attack twice instead of once as long as each attack is made using its Bites attack.

Inflict Greater Disease

Your Summoned Rat Swarm gains two additional uses of Inflict Disease.

In addition, a creature Poisoned by your Summoned Rat Swarm's Inflict Disease ability must make a Constitution Saving Throw against your Ranger Spell Save DC at the end of each of its turns. If the target succeeds on three of these saves, it is no longer Poisoned, and the effect ends. If the target fails three of these saves, the target is no longer Poisoned, but you choose one of the diseases below. The target is subjected to the chosen disease for the remainder of the effect's duration. While affected by a disease as a result of this effect, an affected creature can no longer make a saving throw at the end of each of its turns to end the effect on itself.

Blinding Sickness. Pain grips the creature's mind, and its eyes turn milky white. The creature has disadvantage on Wisdom checks and Wisdom saving throws and is Blinded.

Filth Fever. A raging fever sweeps through the creature's body. The creature has disadvantage on Strength checks, Strength saving throws, and attack rolls that use Strength.

Mindfire. The creature's mind becomes feverish. The creature has disadvantage on Intelligence checks and Intelligence saving throws, and the creature behaves as if under the effects of the confusion spell during combat.

Seizure. The creature is overcome with shaking. The creature has disadvantage on Dexterity checks, Dexterity saving throws, and attack rolls that use Dexterity.

While a creature is under the effect of a disease inflicted by your Summoned Rat Swarm's Inflict Disease feature, you are considered to be concentrating as if you were concentrating on a spell, and if you lose concentration for any reason, the effect ends. If your Summoned Rat Swarm uses its Inflict Disease feature again while a creature is under any effect (One of the Diseases or the Poisoned Condition) of that feature, all previous effects immediately end.

Lord of the Swarm

15th level Rat King feature

You have attained true mastery of your Swarm and of the Rat-like powers you possess, your swarm is strong, poison cannot harm you, and your virulence can affect anyone, even those who would normally be immune to it.

• The Summoned Rat Swarm's Bites attack deals an extra 1d6 Poison Damage (for a total of 2d6 extra damage).
• You and your Summoned Rat Swarm are immune to Poison Damage and the Poisoned condition.
• You and your swarm can treat a creature that is immune to Poison Damage as if it were resistant to Poison Damage instead.
• You and your swarm can treat a creature that is immune to the Poisoned condition as if it wasn't immune to the Poisoned condition, and instead had advantage on saving throws made to avoid or end the Poisoned condition on themselves.