Alternate Traits and Actions
The following changes allow GMs to alter a yowler without modifying its challenge rating.
Decayed Dander (Recharge 5–6). As an action, the yowler can shake loose a cloud of negatively charged, allergenic dander in a 10-foot radius centered on the yowler. Each creature in the area must make a DC 12 Dexterity saving throw, taking 7 (2d6) necrotic damage and becoming poisoned until the end of its next turn on a failed save or half as much damage and not poisoned on a successful one. If a creature’s saving throw fails by 5 or more, the creature is incapacitated until the end of its next turn.
The yowler’s speed is reduced by 10 feet.
Grave Visage. The yowler can project an illusion onto a living creature making the creature appear undead. As a bonus action, it can create this illusion, affecting a Medium or smaller target within 30 feet of it. The target must succeed on a DC 12 Charisma saving throw to avoid this effect. The yowler can only affect one creature at a time, so the effect ends immediately for a creature when the yowler uses Grave Visage, regardless of its success.
The illusion fails to hold up to physical inspection. The target’s skin, for example, would feel smooth, belying the target’s rotting appearance. Without physical contact, a creature must take an action to visually inspect the illusion and succeed on a DC 15 Intelligence (Investigation) check to discern the target’s true appearance.
The yowler loses its Living Projection trait.
Unliving Vengeance. When presented with the yowler’s former master, the yowler gains advantage on attack rolls and Wisdom (Survival) checks to track the target. While it can see or hear its former master, it has disadvantage on attack rolls against all other creatures.
The yowler loses its Yowl action.
Much as feral cats gather into colonies, yowlers can collectively inflict their hatred on the living. They often remain together for longer periods as they aren’t dependent on food sources for survival. Provided they have living creatures to hunt and kill, they benefit from grouping together. This grants them a more powerful version of their terrifying cry and allows them to better maintain the illusion they are normal cats.
Medium swarm of Tiny undead, chaotic evil
Armor Class 12
Hit Points 90 (12d8 + 36)
Speed 40 ft., climb 30 ft.
Skills Perception +2, Stealth +4
Damage Resistances necrotic; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities charmed, frightened, grappled, poisoned, prone, restrained, stunned
Senses darkvision 60 ft., passive Perception 12
Challenge 4 (1,100 XP)
Dander Cloud. If a creature ends its turn adjacent to the yowler clowder or within its space, it must make a DC 13 Constitution saving throw, taking 7 (4d6) poison damage and becoming poisoned until the end of its next turn on a failed save or half as much damage and not poisoned on a successful one. If the creature’s saving throw fails by 5 or more, it is incapacitated until the end of its next turn. A creature adjacent to the swarm has advantage on its save.
Living Projection. The yowler clowder’s undead form is constantly covered with a magical illusion that makes it look like it did in life. If the swarm attacks or uses Yowl, it must succeed on a DC 10 Charisma saving throw or this effect is suppressed for 1 minute. The swarm can repeat the saving throw at the end of each of its turns, allowing the effect to resume on a success.
The changes wrought by this illusion fail to hold up to physical inspection. For example, the swarm’s fur appears soft and silky, but someone touching one of the yowlers would feel its rotten fur and exposed bones. Otherwise, a creature must take an action to visually inspect the illusion and succeed on a DC 17 Intelligence (Investigation) check to discern the swarm’s true appearance.
Swarm. The yowler clowder can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny yowler. The swarm can’t regain hp or gain temporary hp.
Multiattack. The yowler clowder makes two attacks: one with its bites and one with its claws. It can use Yowl in place of a bite attack.
Bites. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 14 (4d6) piercing damage, or 7 (2d6) piercing damage if the swarm has half of its hp or lower. The target must succeed on a DC 13 Constitution saving throw or be poisoned until the end of its next turn.
Claws. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 18 (4d8) slashing damage or 9 (2d8) slashing damage if the swarm has half its hp or lower.
Yowl. The yowler clowder lets loose a cacophony of screams. Each hostile creature within 60 feet of the swarm that can hear it must succeed on a DC 13 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s initial saving throw is successful, the creature is immune to the swarm’s Yowl for the next hour.
New Magic Items and Spells
The following magic item and spell are inspired by the yowler.
Wondrous item, uncommon
When you drape this cloth—stitched together from the hides of several yowlers—over a corpse or undead, the shroud projects an illusion that makes either a corpse appear to be a living, sleeping creature or an undead appear to be an ambulatory, living creature. Any physical interaction with the creature reveals it to be a corpse or an undead because skin texture doesn’t match the displayed texture or the creature has exposed bones. Someone who uses an action to visually inspect the creature identifies the illusory nature with a successful DC 15 Intelligence (Investigation) check.
The illusion lasts until the shroud is removed.
1st-level necromancy (sorcerer, warlock, wizard)
Casting Time: 1 action
Range: Self (30-foot radius)
Components: V, M (a yowler’s whisker)
You unleash an unholy scream. Each creature within 30 feet of you must succeed on a Wisdom saving throw or become frightened until the end of its next turn.
While frightened by this spell, a creature must take the Dash action and move away from you by the safest available route on its turn unless there is nowhere to move.
Yowler Adventure Hooks
- A yowler patiently stalks its owner after killing the groundskeeper that mistreated it. The yowler wasn’t satisfied with killing its tormenter and believes the owner could have done more to protect it when it was a living cat. Presently, the yowler seeks to drive the woman to distraction with constant scratching at windows or piteous howling just after she turns in for the night.
- A night hag has taken a yowler as a familiar and uses the creature to scout out a village to find the most delectable souls. A child somehow saw through the yowler’s illusion, but the villagers attribute his fear of the cat to an overactive imagination.
The Tome Unbound series fleshes out monsters from Tome of Beasts 2, giving GMs ways to modify the existing monsters to surprise well-prepared players or to introduce monsters to a campaign.