Phase Spider 5e: Ethereal Jaunt, Poison and the Spider That Isn't There

A phase spider is a CR 3 Large monstrosity with AC 13, 32 hit points and a poison bite that can leave a character paralyzed for an hour. Its defining trait is Ethereal Jaunt: as a bonus action it shifts between the Material Plane and the Ethereal Plane, where the party can't see or touch it. It appears, bites and disappears. The 2024 phase spider has 45 hit points, bites twice per turn with poison that needs no saving throw, and can see 60 feet into the other plane while it waits.

Table of Contents

• •Phase Spider Stat Block (2014)
• •Phase Spider in the 2024 Rules
• •How Ethereal Jaunt Works
• •How the Phase Spider Fights
• •Running a Phase Spider Encounter
• •How Players Beat a Phase Spider
• •Phase Spider Encounter Ideas
• •Frequently Asked Questions

Phase Spider Stat Block (2014)

The SRD 5.1 phase spider.

On paper, it's fragile: AC 13 and 32 hit points go down to two or three solid hits. It has a single bite, +4 for 7 (1d10 + 2) piercing, and the target makes a DC 11 Constitution save against 18 (4d8) poison damage, half on a success. If that poison damage drops the target to 0 hit points, the target doesn't start dying. It becomes stable, but poisoned for 1 hour even after regaining hit points, and paralyzed while poisoned this way. The spider wants food, not corpses.

Note what it doesn't have: no web attack. Unlike a giant spider, it can't restrain anyone. Web Walker only lets it move through webs freely. Any webs in its lair are terrain, not a weapon.

Phase Spider in the 2024 Rules

SRD 5.2.1 makes the phase spider sturdier and much more dangerous per turn.

The 2024 spider deals roughly double the damage per turn and sees the party from the Ethereal Plane, so it always knows where to come back in. Removing the poison save also removes the party's best defense: a high Constitution no longer helps.

How Ethereal Jaunt Works

The jaunt is a bonus action, and the spider has one bonus action per turn. That fixes its rhythm.

• •On the Ethereal Plane, it can't be seen or affected by creatures on the Material Plane unless something lets them see or reach there. The SRD spells that send creatures to the Ethereal Plane, like Etherealness and Blink, describe it as a gray overlay of the Material Plane where creatures there can only affect each other. It's reasonable to run the spider the same way.
• •Shifting isn't movement. In 2024 the jaunt is a teleport, and teleporting doesn't provoke Opportunity Attacks. In 2014 the shift doesn't use the spider's movement either, so a melee character standing next to it gets no free swing as it vanishes.
• •It can't jaunt in and out on the same turn. One bonus action means one shift per turn.

So a phase spider's turns alternate:

The party gets one round of turns to hit the spider out of every two. Played this way, a 32 HP spider can survive far longer than its numbers suggest.

How the Phase Spider Fights

Ambush from nowhere. With Stealth +6 or +7 and Spider Climb, the spider can wait on a ceiling. More often it just waits on the Ethereal Plane. The 2024 version's Ethereal Sight lets it watch the party from 60 feet away without being seen.

Damage math. Against AC 16:

• •2014: +4 hits on 12 or better (45%). A target with a +2 Constitution save fails DC 11 on a 1 to 8 (40%), so expected poison per hit is about 12.6. With the 7 piercing, a hit averages about 20 damage, or about 9 per turn including misses.
• •2024: +5 hits on 11 or better (50%), twice, for 17 damage each. That's about 17 damage per turn, with no save.

A level 3 cleric with 24 hit points hit by both 2024 bites is at 0, stable and paralyzed for an hour. That ends the cleric's participation in the fight without any death saves.

Pick off the isolated. It goes for the creature at the edge of the light, the one keeping watch, the one who stepped away to scout. Then, when that target is paralyzed, it shifts away and comes back for the next one. It returns to feed once the party is gone or asleep.

Leave when it's hurt. A phase spider at a third of its hit points jaunts out and doesn't come back. On the Ethereal Plane it's safe from almost everything a low-level party has.

Running a Phase Spider Encounter

A phase spider is worth 700 XP. For four characters under the 2024 rules:

Under the 2014 Dungeon Master's Guide guidelines (used by our encounter calculator), two phase spiders are 1,400 XP, multiplied by 1.5 to 2,100. That's past Deadly for four level 4 characters and Medium for four level 5 characters.

The XP math assumes the party can hit what it's fighting. If nobody can see into the Ethereal Plane, treat a phase spider as harder than its CR, and give the party a way to learn about it (a scholar, a survivor, strange bite marks) before the fight.

How Players Beat a Phase Spider

• •Ready an action. The spider appears next to someone. A character with a readied attack ("when the spider appears within reach") gets to strike it before it bites again. This is the single best counter at low level.
• •Stand back to back. Since it has to appear next to a target, a tight formation limits where it can show up, and every arrival is next to two or three readied weapons.
• •Hit it when it's here, hard. On the turns it's on the Material Plane, everyone focuses it. AC 13 and 32 hit points (2014) don't last.
• •See or reach the Ethereal Plane. The See Invisibility spell lets a caster see into the Ethereal Plane. Don't count on Blink: it sends the caster to the Ethereal Plane between turns, where the spider can still reach them, and the caster returns at the start of their own turn without getting to act there.
• •Block it with Wall of Force. In both editions, Wall of Force extends into the Ethereal Plane and blocks ethereal travel through it. A dome around the party keeps the spider out.
• •Cure the paralysis. The bite's paralysis lasts while the Poisoned condition does. Lesser Restoration ends Poisoned in both editions; regular healing doesn't.
• •Save your control spells. Hold Person can't target a Monstrosity. Its weakest saves are Intelligence and Charisma (−2), and its Wisdom is +0, so Wisdom-save spells like Hold Monster have good odds. Command works in 2024, but the 2014 version fails on a creature that doesn't understand your language, and the phase spider speaks none.

Phase Spider Encounter Ideas

The empty camp. A merchant caravan's camp is intact, fire still warm, and every guard is lying stiff in their bedroll, alive but paralyzed. Two phase spiders are still there on the Ethereal Plane, waiting to drag them off. The party arrives minutes after the attack, well inside the hour the poison lasts.

The wizard's mistake. A hedge wizard's tower is overrun because he tried to breed phase spiders for their venom. They escaped through a sealed vault by shifting planes. The party is hired to clear the tower. The wizard needs one spider alive.

Web-reading. In the 2024 rules, a phase spider knows the location of any creature touching the same web. A dungeon corridor is draped in old cobwebs. Every time a character brushes one, the spider knows exactly where they are. Burning the webs is the party's only way to move unseen.

Frequently Asked Questions

What CR is a phase spider in 5e?

A phase spider is CR 3 (700 XP) in both editions. It has AC 13 and 32 hit points in the 2014 rules, AC 14 and 45 hit points in the 2024 rules.

How does Ethereal Jaunt work?

As a bonus action, the phase spider shifts from the Material Plane to the Ethereal Plane or back. While on the Ethereal Plane it can't be seen or affected by creatures on the Material Plane without special magic. It can only shift once per turn because it only has one bonus action.

Does a phase spider's bite paralyze?

Only if the bite drops the target to 0 hit points. The target then becomes stable instead of dying, and is poisoned for 1 hour and paralyzed while poisoned. In the 2014 rules this happens only if the poison damage does it; in 2024, if the bite's damage does.

Can a phase spider make webs?

The SRD phase spider has no web attack. It has Web Walker, which lets it ignore webbing, and in the 2024 rules lets it sense creatures touching the same web. A giant spider is the one that can restrain targets with webs.

Does Ethereal Jaunt provoke opportunity attacks?

No. In the 2024 rules the jaunt is a teleport, which never provokes Opportunity Attacks. In the 2014 rules the shift doesn't use the spider's movement, so it doesn't provoke either.

Stat blocks: System Reference Document 5.1 (2014) and 5.2.1 (2024), Wizards of the Coast, CC-BY-4.0. Tactics, encounter math and ideas are Loreify's own.