Ahdemil, The Warden

Ahdemil, The Warden is a highly, intelligent Blue Dragon that guards The Doorway, the entrance to Ygg Dragun. None can pass without first going through his lair and once they have entered the have never reappeared. The Kobolds of Drak Kul worship and revere him as the "keeper of the gate" and often send their weak, old and malformed to him for what they call: Ascension. 

Each of his scales resemble an ornate tower shield and his wings can be used to blocks even the strongest of attacks. His breath consists of a powerful lightning that makes even the heaviest of metal wearers cower in fear.

Art: Julien Carrasco - Jeex (ArtStation Project: "Heros & Dragons")

The Doorway

Ahdemil, The Warden's lair is The Doorway. It serves as the entrance to Ygg Dragun and as such is guarded with pit falls and collapsible rooftops. The edges of the massive entranceway, the walls and even the floor in most places are petrified from repeated strikes of lightning hitting the surface. The cavern is littered with warped and destroyed metal armors, weapons and trinkets. The air is heavy and the hairs on ones body stand to reach out as if pulled by some unknown force. 

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 16 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 static 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 they may not take reactions 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.

Regional Effects

The region containing Ahdemil, The Warden's lair is warped by the dragon’s magic, which creates one or more of the following effects:

• Thunderstorms rage within the entrance of the lair.
• Dust devils guard the entrance and hallways of the lair. Use the dust devil stat block.
• Hidden pitfalls 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 weak brambling covering the sinkhole must succeed on a DC 15 Dexterity saving throw or fall 1d6 × 10 feet into the sinkhole.

When Ahdemil, The Warden dies, the dust devils disappear immediately, and the thunderstorms abate within 1d10 hours. Any sinkholes remain where they are. Additionally the entrance of the tree is sealed off with a prismatic crystal wall, that is invulnerable and immune to magic. This wall persists until Dublar, The Crowned King  or all the intruding creatures have been slain.