Phase Spider Matriarch

The Phase Spider Matriarch is a type of Monstrosity creature in Baldur's Gate 3. It is a boss encounter in the Whispering Depths and possesses several powerful abilities.

Overview

History

The phase spider matriarch was once an arachnomancer named Eliette and worshipper of Lolth. She wished to transform so as to "refashion myself in the Queen's image".

Combat

Attacks and abilities

 Ethereal Jaunt ()

Surrounded by silver mist, you teleport to an unoccupied space you can see.

 Range: 22 m / 72 ft

Recharge: per turn

 Matriarch's Call ()

The spider matriarch calls on her brood, causing her nearby eggs to hatch.

 Range: 3 m /  ft

Recharge: per turn

 Spider Queen's Wrath

Increase Strength by 2, while  Armour Class is reduced by 1. On Tactician Difficulty: Gain one additional attack per turn. Increase Strength by 2 and grant Resistance to physical damage.

 Range: Self

Recharge: per battle

 Venomous Bite ()

2d6 (2~12) Poison

+

1d8 (1~8) + Dexterity modifier Piercing

+

2d6 (2~12) Poison

Bite a target and possibly Poison it.

Deals 2d6Poison damage and 1d8+4Piercing damage, and possibly injects a venom that deals 2d6Poison damage.

CON Save

 Melee: 1.5 m / 5  ft

 Venomous Discharge ()

4d6 (4~24) + Dexterity modifier Poison

Spit out a venomous substance and possibly  Poison those it hits.

CON Save

 Range: 20 m /  ft

Honour mode

In honour mode only, the matriarch and her Phase Spiders will all have See Invisibility.

 Gossamer Tomb ()

8d10 (8~80) Poison

Entomb a creature that attacks your offspring with an  Infested glob of web.

Unless removed with Fire or Acid damage, this glob of web will eventually explode, dealing 8d10Poison to the entombed creature.

DEX Save

 Range: 30 m / 100 ft

Allies

• 2x Phase Spider
• 18x Phase Spiderling maximum possible, 6 in each group of eggs

Encounter details

• When combat begins, the Matriarch will attempt to hatch her nearby Phase Spiderling eggs. There are three groups of 6 spider eggs scattered throughout the chamber, two on top of the large stone platforms and one at the base of a platform.
• The Phase Spider Matriarch will use its phase abilities to teleport around the arena.
• At 50% or less Hit Points, the Matriarch will cast  Spider Queen's Wrath on itself, entering into an enraged state.
• Knocking the Phase Spider Matriarch into one of the side holes labelled 'Chasm' will kill her and grant the party 250xp. However, knocking her into the centre hole (not labelled 'Chasm') will not grant experience, but its corpse can be found in the Underdark (X:140 Y:151) to loot and possibly animate with Glut. On Tactician and Honour mode, the Matriach cannot be knocked into any of these drops since it will just teleport back to its former location.
• The Phase Spider Matriach has +1 bonuses to Strength and Dexterity on Tactician difficulty, with resultant bonuses to Initiative, Armour Class, Attack rolls, and Saving throws, making an already fairly fierce early game enemy even deadlier.

Tactics

• The Matriarch's eggs can be destroyed before the battle begins if the party can stay hidden (which also allows for an easy Pest Control achievement). Failing that, area damage spells work well on their low Hit Points. It is preferable to destroy all the eggs in Tactician/Honour mode due to her legendary action, but in lower difficulties it can be beneficial to leave a single egg behind in a batch as the Matriarch will essentially waste an action to summon a single Phase Spiderling. Destroying the eggs with Arrow of Fire will destroy nearby web even though it does not damage any webs.^{[See: Bugs]} If any webs are destroyed, A Phase spider will cast  Ethereal Jaunt to find somebody who touch the web soon. on the other hands, Arrow of Acid have no bugs.
• In Honour mode, Spiritual Weapon can be used to kill a Phase Spiderling and the Matriarch will then use Gossamer Tomb on the Spiritual Weapon, but due to the weapon being immune to this action, this will essentially waste the Matriarch's legendary action.
• When the Matriarch is on a web bridge, destroying the bridge using Fire damage will inflict a significant amount of fall damage on her (~45, varying with height). The stone platforms they connect to have no loot on them and are mostly accessible even without the bridges, thus it is recommended to use this tactic whenever the opportunity presents itself.
• Almost all of the Spider Matriarch's damage is Poison so the party can benefit from casting  Protection from Poison or drinking Elixir of Poison Resistance before entering combat.
• 

  The matriarch never initiated combat. Combat log showed 90 exp reward for knocking her down the chasm.
  Lump the Enlightened and his ogres can prove valuable allies in the battle. They can be recruited just up above in the Blighted Village through a Charisma check or paying them 500g. This can result in a win-win situation where Lump is killed in the battle or is significantly weakened allowing the opportunity to easily obtain the Warped Headband of Intellect.
• It's a good idea to spread party members out. Her venomous discharge ability has a large AoE radius.

Exploits

• The middle spiderweb bridge has a stone outcrop that, when the matriarch stands on and the bridge destroyed, would effectively neutralize her: she will be stuck in her falling down animation but never move and, therefore, never enter combat. The combat log gives experience as if she has fallen into the Underdark, but the player can still kill her normally with ranged attacks afterward — yielding the kill experience reward and loot. This was found on a tactician playthrough and should work for honour mode.
  

  A good portion of the matriarch collision size(?) indicator is outside of the ledge.
  • Kill any minions. Having other starting combat for the queen will snap her back to normal.
    • Kill the eggs then the phase spider, use  Minor Illusion to draw them away and into kill-box. Use a rogue and equip them with the Haste Helm for hit-and-run. This should be easy, given all of them have -2 intellect saving throw.
      • Best setup location is the ledge gated by web: draw a spider into the low-ground directly below, activate combat mode first before attacking. Any location with similar advantage is also acceptable.
  • Lure the queen with  Minor Illusion to the outcrop. Attack the bridge then kill her with ranged, as going into melee will trigger normal combat.

Loot

• Poisoner's Robe

Related literature

• Bloody Journal
• Burnt Journal
• Ritual Diagram
• Tattered Journal
• Web-Covered Journal

External links

• Eliette on the Forgotten Realms Wiki