1. Races

Adult Crystal Dragon

Huge Dragon (Gem), typically Chaotic Neutral
AC 16 (natural armor)
Initiative +1 (11)
HP 172 (15d12 + 75)
Speed 40 ft., Burrow 40 ft., Climb 40 ft., Fly 80 ft.
mod
save
mod
save
mod
save
Str
21
+5
+5
Dex
12
+1
+5
Con
21
+5
+9
Int
18
+4
+4
Wis
15
+2
+6
Cha
19
+4
+8
Skills Perception +10Stealth +9Survival +6
Resistances Cold, Radiant
Senses Blindsight 60 ft., Darkvision 120 ft., Passive Perception 20
Languages Common, Draconic, telepathy 120 ft.
CR 12 (XP 8,400, or 10,000 in lair; PB +4) 

Traits

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Multiattack. The dragon makes one Bite attack and two Claw attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage plus 4 (1d8) radiant damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) slashing damage.

Scintillating Breath (Recharge 5–6). The dragon exhales a burst of brilliant radiance in a 60-foot cone. Each creature in that area must make a DC 17 Constitution saving throw, taking 40 (9d8) radiant damage on a failed save, or half as much damage on a successful one. The dragon then gains 15 temporary hit points by absorbing a portion of the radiant energy.

Spellcasting (Psionics). The dragon casts one of the following spells, requiring no spell components and using Intelligence as the spellcasting ability (spell save DC 16):

Bonus Actions

Change Shape. The dragon magically transforms into any creature that is Medium or Small, while retaining its game statistics (other than its size). This transformation ends if the dragon is reduced to 0 hit points or uses a bonus action to end it.

Psychic Step. The dragon magically teleports to an unoccupied space it can see within 60 feet of it.

Legendary Actions

Legendary Action Uses: 3. Immediately after another creature's turn, The dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each of its turns.

  • Claw. The dragon makes one Claw attack.

  • Psionics (Costs 2 Actions). The dragon uses Psychic Step or Spellcasting.

  • Starlight Strike (Costs 3 Actions). The dragon releases a searing beam of starlight at a creature that it can see within 60 feet of it. The target must succeed on a DC 17 Dexterity saving throw or take 31 (9d6) radiant damage.

Lair Actions

On initiative count 20 (losing initiative ties), the dragon can take one of the following lair actions; the dragon can't take the same lair action two rounds in a row:

  • Beguiling Whisper. The dragon telepathically whispers to one creature within range of the dragon's telepathy. The creature must succeed on a DC 15 Wisdom saving throw or be charmed by the dragon until initiative count 20 on the next round. A creature charmed in this way obeys to the best of its ability any command the dragon issues that isn't directly harmful to the creature.

  • Ice Passage. The dragon can open a passage through a wall of ice or snow that is up to 5 feet thick, creating an opening up to 30 feet wide and high.

  • Starlight's Gleam. The dragon chooses a point it can see in the lair. Gleaming starlight radiates from that point to fill a 10-foot-radius sphere with dim light. Each creature other than the dragon in that area when the light appears must succeed on a DC 15 Dexterity saving throw or take 13 (2d12) radiant damage and be outlined in the glow. Attack rolls made against an outlined creature have advantage, and the creature can't hide or benefit from being invisible. The starlight and the glow around any creature fades on initiative count 20 on the next round.

Regional Effects

The region surrounding a legendary crystal dragon's lair is altered by the dragon's magic, creating one or more of the following effects:

  • Clear Skies. The skies above a crystal dragon's lair remain clear and free of precipitation unless magically altered. Winds blow lightly, posing little threat to those approaching the lair, and visibility is the best possible for the time of day.

  • Crystal Profusion. Plentiful quartz crystals form in natural stone within 6 miles of the lair, particularly in places where natural light can shine on the crystals.

  • Icy Sight. Ice and quartz within 6 miles of the lair become conduits for the dragon's psionic presence. As an action, the dragon can cast the clairvoyance spell, requiring no spell components and targeting any ice or quartz crystals in that region.

  • Positive Energy. Any creature that finishes a long rest within 6 miles of the lair regains two additional spent Hit Dice.

  • Thriving Wildlife. Animal populations flourish within 6 miles of the lair. Ability checks made to forage for food by hunting, fishing, or trapping in that area are made with advantage.

If the dragon dies, the animal population near the lair returns to normal levels over the course of 1d10 days. The increased Hit Die recovery ends immediately. The existing abundance of quartz crystals remains, but new crystals form at a normal rate.

Customizing DragonsFTD p33[–]

You can customize any dragon's stat block to reflect the dragon's unique character. Minor changes such as those below are easy to make and have no impact on a dragon's challenge rating.

Languages. Most dragons prefer to speak Draconic but learn Common for dealing with allies and minions. But given their high Intelligence and long life span, dragons can easily learn additional languages. You can add languages to a dragon's stat block.

Skills. Most dragons are proficient in the Perception and Stealth skills, and many dragons have additional skill proficiencies. As with languages, you can customize a dragon's skill list (even doubling their proficiency bonus with certain skills) to reflect particular interests and activities. You can also give a dragon tool proficiencies, particularly if the dragon spends time in Humanoid form.

Other Traits and Actions. You can borrow traits and actions from other monsters to add unique flavor to a dragon. Consider these examples:

  • Change Shape. You can decide that a dragon acquires this action at a younger age than usual, particularly if you want to feature a dragon in Humanoid form in your campaign:The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the dragon's choice).In a new form, the dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

  • Flyby. The dragon is an agile flier, quick to fly out of enemies' reach.The dragon doesn't provoke an opportunity attack when it flies out of an enemy's reach.

  • Mimicry. Impersonating characters or their allies could be a fun trick for a crafty dragon.The dragon can mimic any sounds it has heard, including voices. A creature that hears the sounds can tell they are imitations with a successful DC 12 Wisdom (Insight) check.

  • Rejuvenation. You might decide that dragons in your campaign, being an essential part of the Material Plane, are nearly impossible to destroy. A dragon's life essence might be preserved in the egg from which it first emerged, in its hoard, or in a cavernous hall at the center of the world, just as a lich's essence is hidden in a phylactery.If it has an essence-preserving object, a destroyed dragon gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the object.

  • Special Senses. Most dragons have blindsight and darkvision. You might upgrade blindsight to truesight, or you could give a dragon with a burrowing speed tremorsense.

  • Tunneler. The dragon can burrow through solid rock at half its burrowing speed and leaves a tunnel in its wake.

Source: FTD, page 171.