Iymrith

From Storm King's Thunder, page 241.

**Hit Points:** 481 (26d20 + 208)
 **STR**
29 (+9)
10 (0)
27 (+8)
18 (+4)
17 (+3)
 **Saving Throws:** Dex +7, Con +15, Wis +10, Cha +12
**Skills:** Perception +17, Stealth +7
**Damage Immunities:** lightning
**Senses:** blindsight 60 ft., darkvision 120 ft., passive Perception 27
**Languages:** Common, Draconic, Giant, Terran
 ***Innate Spellcasting.*** Iymrith's innate spellcasting ability is Charisma (spell save DC 20). Iymrith's stone shape can create a living gargoyle instead of altering the stone as described in the spell description. This transformation is permanent and can't be reversed or dispelled. She can innately cast the following spells, requiring no material components:
*1/day:* Counterspell, Detect Magic, Ice Storm, Stone Shape, Teleport
 ***Multiattack.*** Iymrith can use her Frightful Presence. She then makes three attacks: one with her bite and two with her claws.
***Bite.** Melee Weapon Attack:* +16 to hit, reach 15 ft., one target. *Hit:* 20 (2d10 + 9) piercing damage plus 11 (2d10) lightning damage.
***Claw.** Melee Weapon Attack:* +16 to hit, reach 10 ft., one target. *Hit:* 16 (2d6 + 9) slashing damage.
***Tail.** Melee Weapon Attack:* +16 to hit, reach 20 ft., one target. *Hit:* 18 (2d8 + 9) bludgeoning damage.
***Frightful Presence.*** Each creature of Iymrith's choice that is within 120 feet of Iymrith and aware of her must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Iymrith's Frightful Presence for the next 24 hours.
***Lightning Breath (Recharge 5-6).*** Iymrith exhales lightning in a 120-foot line that is 10 feet wide. Each creature in that line must make a DC 23 Dexterity saving throw, taking 88 (16d10) lightning damage on a failed save, or half as much damage on a successful one.
***Change Shape.*** Iymrith magically polymorphs into a female Storm Giant or back into her true form. She reverts to her true form if she dies. Any equipment she is wearing or carrying is absorbed or borne by the new form (Iymrith's choice).
 Iymrith can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Iymrith regains spent legendary actions at the start of its turn.
**Detect.** Iymrith makes a Wisdom (Perception) check.
**Tail Attack.** Iymrith makes a tail attack.
 On initiative count 20 (losing initiative ties), Iymrith takes a lair action to cause one of the following effects; Iymrith can't use the same effect two rounds in a row:
* Part of the ceiling collapses above one creature that Iymrith can see within 120 feet of her. The creature must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) bludgeoning damage and be knocked prone and buried. The buried target is restrained and unable to breathe or stand up. A creature can take an action to make a DC 10 Strength check, ending the buried state on a success.
* A cloud of sand swirls about in a 20-foot-radius sphere centered on a point Iymrith can see within 120 feet of her. The cloud spreads around corners. Each creature in the cloud must succeed on a DC 15 Constitution saving throw or be blinded for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
 The region surrounding Iymrith's lair is warped by Iymrith's magic, which creates one or more of the following effects:
* Thunderstorms rage within 6 miles of the lair.
* Dust devils scour the land within 6 miles of the lair. A dust devil has the statistics of an Air Elemental, but it can't fly, has a speed of 50 feet, and has an Intelligence and Charisma of 1 (-5).
* Hidden sinkholes form in and around Iymrith's lair. A sinkhole can be spotted from a safe distance with a successful DC 20 Wisdom (Perception) check. Otherwise, the first creature to step on the thin crust covering the sinkhole must succeed on a DC 15 Dexterity saving throw or fall 1d6 x 10 feet into the sinkhole.

If Iymrith dies, the dust devils disappear immediately, and the thunderstorms abate within 1d10 days. Any sinkholes remain where they are.