Huge aberration, neutral evil

Armor Class 17 (natural armor)
Hit Points 228 (24d12 + 72)
Speed 30 ft.

22 (+6) 16 (+3) 17 (+3) 19 (+4) 14 (+2) 18 (+4)

Skills Perception +12, Stealth +8
Damage Resistances fire, lightning
Damage Immunities cold
Senses darkvision 120 ft., passive Perception 17
Languages Common, Undercommon; telepathy 60 ft.
Challenge 15 (13,000 XP)


  • Drain Memories. The hyakume targets one creature it has touched. The target must succeed on a DC 18 Wisdom saving throw or take 44 (8d10) psychic damage and become memory drained until it finishes a short or long rest or until it benefits from the greater restoration or heal spell. Constructs, oozes, plants, and undead succeed on the save automatically. While memory drained, the target must roll a d4 and subtract the number rolled from any ability check or attack roll it makes. Each time the target is memory drained beyond the first, the die size increases by one: the d4 becomes a d6, the d6 becomes a d8, and so on until the die becomes a d20, at which point the target becomes charmed for 1 hour. The effect then ends. When a hyakume causes a target to become memory drained, the hyakume gains full access to these memories, learns all the languages the target knows and gains all its proficiencies, except any saving throw proficiencies. It may also transfer these memories to a willing creature it touches.


  • Multiattack. The hyakume can use his Maddening Presence and then make three slam attacks.
  • Slams. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 24 (4d8 + 6) bludgeoning damage and the target is exposed to his drain memories trait. If the target is a creature, the hyakume can choose one of the following additional effects:
    • The target must succeed on a DC 19 Strength saving throw or drop one item it is holding (hyakume’s choice).
    • The target must succeed on a DC 19 Dexterity saving throw or be knocked prone.
    • The target must succeed on a DC 19 Constitution saving throw or be stunned until the end of the hyakume’s next turn.
    • The damage of the attack is converted to cold, force, psychic or thunder damage.
  • Eye Probe (1/Day). The hyakume can detach up to six of its eyes and send them on missions. An eyeball has AC 22, hp 5, and a fly speed of 60 ft. (hover). The hyakume can see through all of its eye probes and can make drain memory attacks with them. If a hyakume’s eyeball is destroyed, the hyakume takes 5 points of damage. An eye probe can’t stray farther than 1 mile from the hyakume or the eye is destroyed (dealing 5 points of damage).
  • Maddening Presence. The hyakume targets one creature it can see within 30 feet of it. If the target can see or hear the horror, the target must make a DC 17 Wisdom saving throw. On a failed saving throw, the target becomes paralyzed until the end of its next turn. If a creature’s saving throw is successful, the creature is immune to the hyakume’s Maddening Presence for the next 24 hours.


Hideous and corpulent, with numerous eyes dotting their bodies, hyakumes are mystics of malevolence. They steal and collect the memories of other intelligent beings to increase their own knowledge. These hundred-eyed horrors can see in all directions physically, but they also perceive the minds and thoughts of those nearby and they hunger for them. In some unknown way, they crave to consume thoughts and memories, providing psychic sustenance to them in a way incomprehensible to other beings. They can flood their own alien and terrible thoughts back into the minds of those nearby, driving them to the brink of madness and beyond with an overwhelming flood of captured yet inchoate emotion and shattered rationality.

Section 15: Copyright Notice

Asian Monsters (5E) © 2021, Legendary Games; Authors Miguel Colon, Jason Nelson, Andrew Ha, Aurélien Lainé, Dan Dillon, Ismael Alvarez, James-Levi Cooke, Robert J. Grady, Jeff Ibach, Matt Kimmel, and Thurston Hillman

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