Many unusual creatures roam the underdark, but few are quite as unusual as the uncommon ghost spider. What initially appears to be an odd translucent spider – if it appears at all – quickly reveals itself to be a deadly psionic threat, and one of the more dangerous members of the arachnid family.
A unique predator
Hapless prey that wanders into the territory of a ghost spider will quickly become paranoid, hearing clicking and scraping from all directions and seeing vague movement at the corners of its vision. The ghost spider has the ability to psionically invade the minds of other creatures, allowing it to subtly manipulate its targets into separating from friends or travel down dangerous and isolated pathways. The ghost spider uses this power to create complex illusory images of blocked hallways, dangerous creatures, or other common underdark encounters, with the intent to lead its prey directly underneath it to strike.
Suspending itself from a glowing mushroom cap, almost invisible, a ghost spider will drop down with a pre-prepared net of webs to ensnare a lone creature, or single out a creature during a commotion. The hapless creature is then pulled upwards to the roof of the mushroom or ceiling, where the ghost spider will quickly bind the creatures mouth, inject paralyzing venom, and then carry them away to its lair for safekeeping.
While a ghost spider can technically communicate telepathically with other creatures, doing so rarely results in more than a general sense of unease and faint echoes of chittering in the recipient’s mind due to the alien nature of the spider’s thoughts.
Dangerous alone, deadly together
By itself, a ghost spider will act as an ambush predator – only striking when it feels it has the advantage. This might be against a lone target, or against a single target out of a distracted group. While in a ghost spider’s territory, adventurers should be extremely wary when embroiled with other creatures, lest they find one party member missing at the end of the fight.
When hunting in packs, as they have been known to do when food is scarce, ghost spiders will begin by panicking their prey using visions of extreme danger; hook horrors, umber hulks, and other monsters are commonly employed to trick their prey into fleeing and disbanding. Illusory walls and fake pathways will work towards splitting groups apart, and the spiders will ultimately strike at their prey as a group, often alongside mirror images of themselves. Many victims of ghost spiders never become aware of their presence, believing until their final moments that the illusory beasts in their minds were their downfall.
View statblock as image
Large monstrosity, unaligned
|Armor Class 14 (natural armor)
Hit Points 38 (6d10 + 5)
Speed 30 ft., climb 30 ft.
|Skills Stealth +9
Senses Darkvision 60ft, Passive Perception 11
|Spider Climb. The spider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Web Walker. The spider ignores movement restrictions caused by webbing.
Psionic Sense. Ghost spiders can sense and detect the location of all living creatures within 120ft of their lair, as long as those creatures are not protected against psionics.
Illusive. Ghost spiders have advantage on saving throws against spells from the school of illusion.
|Innate Spellcasting. The spider’s spellcasting ability is wisdom (spell save DC 11). It can innately cast the following spells, requiring no material components:
At will: minor illusion, major image
1/day: mirror image
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 18 (4d8) poison damage on a failed save, or half as much damage on a successful one. Furthermore, on a failed save the creature has disadvantage on all wisdom saves against the ghost spider for 10 minutes as their mind is made more susceptible to the spider’s influence. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.
Illusory Danger. The ghost spider chooses a target within 30ft that it can see. That target must make a DC 11 wisdom saving throw, taking 9 (2d8) psychic damage on a failed save. Furthermore, on a failed save the target no longer sees the ghost spider as the most dangerous threat, and will instead put their efforts towards strategising or defending against an illusionary danger appropriate to the area. They may act confused as to why any allies would choose to focus on the spider instead. This effect persists for one minute. The creature can repeat the saving throw at the end of each of its turns, ending the effect on a success. Only one creature can be under the effect of this ability at a time.
Distracting Visions. When hit by an attack from another creature, a ghost spider may use its reaction to inject alarming images of danger into the mind of its aggressor. The attacking creature must make a DC 11 wisdom saving throw. On a failure, the attack misses instead of hitting.
- Ghost spiders are fiercely protective of their eggs. They can emit a specialised shriek that alerts other ghost spiders nearby that an egg sac is threatened, quickly multiplying any threat.
- Ghost spider egg sacs are valuable for their alchemical properties, with each one being the size of a cat and fetching around 200 gold.
- The egg sacs can be alchemically brewed into potions of psionic resistance; those who imbibe such potions become resistant to psionic damage and have advantage against illusory effects, for up to ten minutes – depending on the skill of the alchemist.
- Ghost spider venom can be extracted and placed on arrow tips or streaked across sword blades. A single ghost spider can fill three small vials, with each vial being enough for a single use.
- When used as a solo creature, ghost spiders work best during encounters with other creatures. Have the initial encounter start, and then have the ghost spider’s illusions disrupt the fight further. During the commotion, abduct one of the players; this can result in a hectic chase scene where the players must catch the spider while still engaged with the original encounter, or perhaps a small search-and-rescue arc can ensue after the players defeat the first encounter and realise that one of their party is missing.
- When hunting in packs, take full advantage of the spider’s ability to innately cast major image; close off passages that the players have already walked through to prevent them from leaving, and use images of danger to force the players into disadvantageous terrain.
- The illusory danger ability is based on the local area. Use it as an opportunity for the players to engage in interesting roleplay, believing that there is other pressing danger nearby and trying to convince their party of the same.
- Ghost spiders are still only spiders, and have low intelligence. While they have powerful illusion magic, these illusions are limited to what a spider might choose to conjure. They instinctively know to herd their prey and how to mimic other dangerous creatures, but will never have the wherewithal to create illusions of humanoids, writing, or other such intelligent ploys.