Adult Prismatic Dragon

The rarest of true dragons, prismatic dragons are perhaps the most chaotic. While some are playful, others are aggressive, with the majority trending towards chaotic neutral. A Prismatic dragon is rarely malicious, but often ignores morality completely, acting mostly on primal whims. A prismatic dragon is muscular, with a solid jaw and many sharp edges. Perhaps the most unique feature of a prismatic dragon is it’s hide, which flickers across all colours of the visible spectrum. Many prismatic dragons enjoy discovery and learning and as such it is not unusual to find that a dragon has taken some interest in either the sciences and/or magic. 

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:

• Grasping roots and vines erupt in a 20-foot radius centered on a point on the ground that the dragon can see within 120 feet of it. That area becomes difficult terrain, and each creature there must succeed on a DC 15 Strength saving throw or be restrained by the roots and vines. A creature can be freed if it or another creature takes an action to make a DC 15 Strength check and succeeds. The roots and vines wilt away when the dragon uses this lair action again or when the dragon dies.
• A wall of tangled brush bristling with thorns springs into existence on a solid surface within 120 feet of the dragon. The wall is up to 60 feet long, 10 feet high, and 5 feet thick, and it blocks line of sight. When the wall appears, each creature in its area must make a DC 15 Dexterity saving throw. A creature that fails the save takes 18 (4d8) piercing damage and is pushed 5 feet out of the wall’s space, appearing on whichever side of the wall it wants. A creature can move through the wall, albeit slowly and painfully. For every 1 foot a creature travels through the wall, it must spend 4 feet of movement. Furthermore, a creature in the wall’s space must make a DC 15 Dexterity saving throw once each round it’s in contact with the wall, taking 18 (4d8) piercing damage on a failed save, or half as much damage on a successful one. Each 10-foot section of wall has AC 5, 15 hit points, vulnerability to fire damage, resistance to bludgeoning and piercing damage, and immunity to psychic damage. The wall sinks back into the ground when the dragon uses this lair action again or when the dragon dies.
• Magical fog billows around one creature the dragon can see within 120 feet of it. 

Regional Effects

The region containing a legendary prismatic dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:

• All non-magical darkness within 1 mile of the dragon’s lair becomes dim light. The light is sourceless and it’s colour fluctuates slowly at all times. 
• Within 1 mile of its lair, valuable minerals and gemstones form at an abnormally fast rate. All kinds of minerals and gemstones form, growing up to 20 inches tall and often being of abnormally high quality. These materials are strongly attached to the environment and often shatter when removed. A creature attempting to harvest such materials must make a DC 20 sleight of hand check to remove the gem with major damage. On a roll of 25 tp 29 there is only minor damage to the gem. On a roll of 30 or higher the gem is removed undamaged. 

If the dragon dies, the rodents and birds lose their supernatural link to it. The thickets remain, but within 1d10 days, they become mundane plants and normal difficult terrain, losing their thorns.