Glaucus Slug, Giant

Small beast, unaligned

Armor Class 12
Hit Points 49 (9d6 + 18)
Speed 0 ft., swim 30 ft.

14 (+2) 15 (+2) 15 (+2) 1 (-5) 12 (+1) 2 (-4)

Damage Resistances poison
Condition Immunities charmed, frightened
Senses darkvision 30 ft., passive Perception 11
Challenge 2 (450 XP)
Proficiency Bonus +2


  • Reactive. The slug can take one reaction on every turn in combat


  • Multiattack. The slug attacks twice with its cerata.
  • Cerata. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 5 (1d6 + 2) bludgeoning damage plus 3 (1d6) poison damage, and the target must succeed on a DC 12 Constitution saving throw or be poisoned for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
  • Tongue. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) piercing damage. If the target is a venomous creature, the slug extracts venom and stores it in its cerata. For 1 hour, the slug’s cerata attack deals an extra 3 (1d6) poison damage on a hit.


  • Reactive Sting. When a creature touches the slug or hits it with an unarmed melee attack while within 5 feet of it, the slug makes a cerata attack against that creature.


Sailors’ tales are full of fantastical creatures and monstrous beasts. While some who spend all their days on land might think these stories are exaggeration or imagination, those who have sailed the seas know there is more truth to them than not. From giant squid to jellyfish, strange creatures inhabit the depths of the world’s oceans. Every ship that sails the sea is bound to encounter such a creature sooner or later. One of the lesser-known of these ocean dwellers is the giant glaucus slug, a monstrously oversized version of the common blue glaucus sea slug.

Like their miniature kin, these shell-less mollusks float upside down on the water’s surface using their long, slender appendages called cerata to create surface tension. They do not locomote on their own but instead rely on winds and ocean currents to drift across the sea. A glaucus slug’s blue and silver coloration acts as camouflage, blending into the deep blue of ocean water from above and the white reflected sunlight from the ocean’s surface from below. While the silhouette of a glaucus slug resembles the outstretched wings of a dragon, these aquatic animals bear no relation to true dragons, despite their colorful alternative name, blue dragon slugs. By themselves, glaucus slugs are not especially dangerous. However, swimmers and sailors should still be wary when a glaucus slug appears. They both serve as a warning that venomous jellyfish may be nearby and can be deadly to encounter themselves when full of fresh jellyfish venom. The paralytic venom can leave the unfortunate victim vulnerable in the water to other animals’ attacks.

Glaucus slugs are one of the few animals capable of eating highly toxic jellyfishes.

Perhaps even more terrifyingly, the glaucus can store-and even concentrate- consumed venom to use against future prey.

Section 15: Copyright Notice

Battlezoo Bestiary (5E) © 2022, Skyscraper Studios, Inc.; Authors: William Fischer, Stephen Glicker, Paul Hughes, Patrick Renie, Sen.H.H.S., and Mark Seifter.

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