Swarm of Spiders
Medium Beast (Swarm), unaligned
100 XP
Special Abilities
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 insect. The swarm can't regain hit points or gain temporary hit points.
Spider Climb
The swarm can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Web Sense
While in contact with a web, the swarm knows the exact location of any other creature in contact with the same web.
Web Walker
The swarm ignores movement restrictions caused by webbing.
Actions
Bites
Melee Weapon Attack: +3 to hit, reach 0 ft., one target in the swarm's space. Hit: 10 (4d4) piercing damage, or 5 (2d4) piercing damage if the swarm has half of its hit points or fewer.
Quick Reference
Running This Encounter
The Swarm of Spiders excels at creating a sense of dread and encirclement rather than dealing massive damage. Use them to control space, block corridors, and force players into difficult positioning decisions. Their climbing ability makes them unpredictable—they can emerge from walls, ceilings, and tight spaces, making preparation and awareness crucial. Consider combining them with a larger spider or arachnid boss for a thematic encounter with layered threats.
Combat Tactics
The swarm prioritizes swarming a single target to maximize its pack damage output, dealing 4d4+2 piercing damage on a hit. They attempt to restrain and immobilize prey by climbing over and around targets, using their mobility to flanking advantage. When facing multiple opponents, they divide but maintain cohesion, staying close enough to support each other while exploiting narrow passages where their small size is an advantage.
Environment & Setting
This swarm thrives in dark, web-filled caverns, abandoned buildings with corners and crevices, or dense forests with plenty of vertical terrain. Encounters work best in environments with difficult terrain, pillars, or natural obstacles that reward the spiders' climbing speed and punish straightforward tactics.