Iymrith

Traits

Legendary Resistance (3/Day)

If Iymrith fails a saving throw, she can choose to succeed instead.

Actions

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 it 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).

In storm giant form, Iymrith retains her alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Her statistics are otherwise replaced by those of the new form.

Legendary action uses: 3. The creature can use one option at the end of another creature’s turn and regains spent uses at the start of its turn.

Legendary actions

Detect

Iymrith makes a Wisdom (Perception) check.

Tail Attack

Iymrith makes a tail attack.

Wing Attack (Costs 2 Actions)

Iymrith beats her wings. Each creature within 15 feet of Iymrith must succeed on a DC 24 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage and be knocked prone. Iymrith can then fly up to half her flying speed.

Spellcasting

Iymrith casts one of the following spells, requiring no spell components and using Charisma as the spellcasting ability (spell save DC 20):

1/day each: detect magic, dispel magic, ice storm, stone shape, teleport

When she casts her stone shape spell, Iymrith can shape the targeted stone into a living gargoyle instead of altering the stone as described in the spell's description. This transformation is permanent and can't be reversed or dispelled.

Lair actions

On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects; the dragon can't use the same effect two rounds in a row:

• Part of the ceiling collapses above one creature that the dragon can see within 120 feet of it. 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 the dragon can see within 120 feet of it. 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.
• Lightning arcs, forming a 5-foot-wide line between two of the lair's solid surfaces that the dragon can see. They must be within 120 feet of the dragon and 120 feet of each other. Each creature in that line must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) lightning damage.

Additional Lair Actions

At your discretion, a legendary (adult or ancient) blue dragon can use one or both of the following additional lair actions while in its lair:

• Misleading Mirage: Until initiative count 20 on the next round, at each intersection or branching passage in the lair, a creature other than the dragon has a 50 percent chance of going in a different direction from the direction it intends.
• Sudden Sinkhole: The dragon chooses a point on the ground that it can see within 120 feet of it. A 5-foot-radius, 20-foot-deep pit forms centered on that point. A creature on the ground above where the pit formed must make a DC 15 Dexterity saving throw. On a failed save, a creature falls to the bottom of the pit, taking 7 (2d6) bludgeoning damage and landing prone. On a successful save, a creature moves to the nearest unoccupied space instead of falling in the pit.

Regional effects

The region containing a legendary blue dragon's lair is warped by the dragon'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 the dragon'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 × 10 feet into the sinkhole.

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

Additional Regional Effects

Any of these effects might appear in the area around a blue dragon's lair, in addition to or instead of the effects described in the Monster Manual:

• Blue Luster: Creatures that spend a year within 1 mile of the dragon's lair find blue objects fascinating and feel compelled to acquire them at every opportunity.
• Mirage Terrain: The area immediately surrounding the lair appears to be a lush oasis. A creature carefully examining the illusion can attempt a DC 15 Intelligence (Investigation) check to disbelieve it. A creature who disbelieves the illusion sees it as a vague image superimposed on the underlying terrain.
• Sandstorm: A sandstorm blows constantly within 1 mile of the dragon's lair.