Swarm of Ice Borers

Medium swarm of Tiny Elementals, unaligned

Armor Class 12
Hit Points 40 (9d8)
Speed 10 ft., climb 10 ft., fly 30 ft. (hover)

7 (–2) 15 (+2) 10 (+0) 3 (–3) 10 (+0) 3 (–4)

Skills Stealth +4
Damage Resistances bludgeoning, piercing, slashing
Damage Immunities cold Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses passive Perception 10
Challenge 2 (450 XP)
Proficiency Bonus +2


  • False Appearance. While the swarm remains motionless, it is indistinguishable from a cluster of icicles. This trait doesn’t function if the swarm has damaged a creature with blood within the past 2 hours.
  • Frigid Mass. A creature that starts its turn in the swarm’s space takes 4 (1d8) cold damage.
  • Heatsense. The swarm can pinpoint the location of creatures emitting heat, such as warm-blooded Beasts and Humanoids, within 30 feet of it.
  • Spider Climb. The swarm can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
  • Swarm. The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny elemental. The swarm can’t regain hp or gain temporary hp.


  • Impale. Melee Weapon Attack: +4 to hit, reach 0 ft., one creature in the swarm’s space. Hit: 7 (2d6) piercing damage plus 9 (2d8) cold damage, or 3 (1d6) piercing damage plus 4 (1d8) cold damage if the swarm has half its hp or fewer.


The simple icicle moves, unfurling delicate, icy wings. As it reveals a hungry, gnawing mouth full of piercing teeth, dozens more follow suit.

Creatures originally from deep within the elemental planes, ice borers resemble a shard of ice at first glance. They have thin, membranous wings that they keep wrapped tight to their bodies when not in flight, and their mouths look like cracks in the ice when closed. The icicle façade fades instantly if an ice borer has eaten recently, as its body gains a red tint from the consumed blood.

Patient Hunters. Ice borers are carnivorous and station themselves above entrances to caves and on the eaves of buildings where icicles form. Hidden among the mundane icicles, a group of ice borers will wait for a hapless creature to walk beneath them, waiting to sense the warmth of a living creature. When a suitable victim approaches, they launch themselves from their perches to fall into their feast. If threatened by a particularly powerful foe or if their meal wasn’t as easy as they thought, a swarm of ice borers takes wing to find a safer place to hunt.

Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

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