Maddening Visage. The writhing mass of tails binding the individual members of the Rat King together coil in impossible ways causing madness in the weak minded. A creature looking at the Rat King at the beginning of it's turn must pass a DC 17 Intelligence save or suffer the effects of the Confusion spell for that turn. Once a creature passes any of these tests it becomes immune for 24 hours. On a turn after suffering the effects It must take another save as no chance to regain ones senses and look away is possible.
Undying Dominion. All types of rats that die within 15 miles of a Rat King are raised from the dead as a zombie version of themselves at the beginning of their next turn unless killed with fire, radiant, acid, or necrotic damage.
Averse to Light. The Rat King is born of shadows and anything that casts away shadows is anathema to it and weakens it. Any creature in an area of bright light targeted by one of the Rat King's abilities or spells has advantage on it's saving throw. If the Rat King begins it's turn within an area of bright light it suffers 1d6 radiant damage and cannot regain hit points from any effect while within an area of bright light.
Innate Spellcasting (Psionics). The Rat King's innate spellcasting ability is Intelligence (spell save DC 17, +9 to hit). It can innately cast the following spells, requiring no components:
At Will: detect thoughts, darkness, animal messenger (rats), ray of enfeeblement
3/day: blight, contagion, fear, phantasmal killer
1/day each: circle of death, eyebite, finger of death, forbiddance, harm
Shadow Wreath. The Rat King targets every creature within 30 feet of it. Each creature must pass a Dexterity or Strength saving throw (their choice) on a DC 17 or be restrained by grasping shadows. A restrained creature may use an action on each of it's turns to repeat this save.
Mire the Mind. The Rat King exerts it's psychic dominance over a creature within 60 feet of its every thought and action. For the next minute that creature must pass a Wisdom saving throw at the beginning of each of it's turns or be Stunned until the start of it's next turn. This effect ends immediately if the Rat King uses this action on another creature.
Spectre of the Underworld (1/day). The Rat King emits a pulse of psychic energy ripping apart the minds of everything around it. All creatures within 60 feet of the Rat King must make a Wisdom saving throw suffering 33(6d10) psychic damage on a failed save and half as much on successful save. Any creature reduced to 0 hit points by this ability is not killed but instead has it's Wisdom, Intelligence and Charisma all reduced to 1 and it becomes permanently Stunned. This effect is only reversible with a power word heal or wish spell or
The Rat King can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The Rat King regains spent legendary actions at the start of its turn.
Psionics (Costs 1 action). The Rat King casts any one of its At Will Psionic spells.
Shadow Wreath (Costs 2 actions). The Rat King takes a Shadow Wreath action.
Mire the Mind (Costs 2 actions). The Rat King takes a Mire the Mind action.
Description
A large enough population of rats will inevitably spawn a Rat King, a master of negative energy that comes to dominate the darker places of the world. Large cities inevitably have a Rat King deep within the sewers, basements or thieves tunnels that riddle them. As rats scurry over each other their tails tie together, unable to move the rats panic, clawing and biting furiously to free themselves, usually with some success. Occasionally though far too many are tied and cannot be freed. When but one is left alive struggling the built up aura of fear, rage and desperation allows necrotic energy to pour in from the negative plane transforming the rat bundle into an abomination, a natural ruler of the darkness of the world.
Patron of Thieves. Natural rulers of the underworld, Rat Kings often interfere in the local underbelly of civilization and gain leadership over bands of thieves, and assassins sometimes even ruling cities through veins of subterfuge and intricate plotting.
Lair and Lair Actions
The lair of a Rat King is typically the depth of a sewer or large open area deep underground beneath a city.
Lair Actions
When fighting inside it's lair the Rat King can use lair actions. On initiative count 20 (losing initiative ties), the Rat King can take one lair action to cause one of the following effects: the Rat King can't use the same lair action two rounds in a row.
- 1d6 Swarms of Shade Rats (swarm of rats but with immunity to necrotic and psychic damage) spawn and always act last each round. Each must spawn in an area of darkness but in a location of the Rat King's choosing.
- The Rat King causes the shadows within it's lair to draw the life force of his enemies towards him and replenish his own. All enemy creatures within the lair not in an area of bright light suffer 2d6 necrotic damage, healing the Rat King for half of the total damage dealt.
- The Rat King snuffs out all non-magical light sources within it's lair and all magical light sources produced by a 2nd level or lower spell.