Ancient Red Dragon's Lair

Cell Cellar

• Earthquakes still in affect.
• Darkvision rules still apply.
• Roll 1d4 for Kobolds in cellar.

1.

• Staircase leads to stone hallway with three hallways branching off on both the left and right. Unlit torches on walls.
• Each hallway leads to a door.
• First door on left leads is locked. Leads to cavern.
• Second door on left is crushed by cave-in.
• Third door on left is locked. Leads to cell with single bucket for poop and bones. Smells bad.
• First door on right unlocked. Leads to room with table and three barrels. Unlit torch in room. Barrels contain rotten food. Iron key ring with keys on table.
• Second door on right is locked. Leads to cell with single bucket for poop and bones. Smells bad.
• Third door on right is crushed by cave-in.

Cavern

• Earthquakes still in affect.
• Darkvision rules still apply. Unless in chamber with lava.
• Boiling Water: All of the water in and around cave is boiling hot. Any creature that touches or attempts to wade through the water takes (2d6) fire damage.
• Lava and Magma: The biggest natural danger in the cave is the magma itself. The magma is very difficult to move through. Near the lava’s “shores” a creature at half speed through the lava. Towards the center of the magma pools, the lava can be as much as 30 feet deep, requiring that a creature swim its way through with a similar penalty to movement. Creatures of his cave suffer no penalty when swimming through magma and lava.
  When a creature touches the magma, it immediately takes (4d10) fire damage or (10d10) fire damage if it is completely submerged. If a creature remains within the magma, it takes an additional (10d10) fire damage at the start of each of its turns. Any flammable, nonmagical object that the creature is wearing or carrying is immediately destroyed by the magma. Metal items are also quickly destroyed by the magma’s intense heat. A weapon takes a permanent and cumulative -3 penalty to damage rolls as long as it is submerged in the magma. If its penalty drops to -5 or less, it is destroyed. Nonmagical ammunition made of metal that hits the lava is destroyed on contact. Nonmagical armor worn by a creature submerged in lava takes a permanent and cumulative -3 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10 or less.
  A creature whose hit points are reduced to 0 from the magma is completely dissolved. The creature can be restored to life only by means of a true resurrection or wish spell.
  The lava exudes extreme heat as well. Checks made to avoid exhaustion due to Extreme Heat start at DC 10 when within 30 feet of lava. And a creature that starts its turn within 5 feet of lava automatically takes (2d6) fire damage. Furthermore, flammable objects in the same range that aren’t being worn or carried ignite.
  The creatures immune to fire that live in the cave use the lava to their advantage. Fire immune creatures will hide in the lava, which offers full cover, then work to push those that aren’t immune to it into it.

Ceilings

• The majority of the cave has 60 foot high ceilings. However, the ceilings over the magma lake are 100 feet high. The narrow passages on the north and northwestern end are tighter, as low as 4 feet high at some points.

2.

• Boiling Water: All of the water in and around cave is boiling hot. Any creature that touches or attempts to wade through the water takes (2d6) fire damage.
• Steam: Another side effect of the boiling water is its steam. The air over any water in the cave is heavily obscured and any area within 30 feet of the water is lightly obscured as well. Any creature passing through steam must also succeed on a DC 10 Constitution saving throw or take (2d6) fire damage.
• Geyser Cave: Unsurprisingly, geysers of scalding hot water regularly take place in the Geyser Cave. On initiative count 20, a creature over or within 5 feet of the water must make a DC 15 Dexterity saving throw or take (4d6) fire damage and be knocked prone, or take half as much damage on a success and isn’t knocked prone. The hot waters in the geyser cave make it difficult to see dangers within the cave, as well (see Steam and Boiling Water above).
  Within the extreme steam and boiling waters of the geysers emerge two types of elementals: three Steam Elementals and three Water Elementals. The Water Elementals are scalding hot. When either elemental type enters another creature’s space using its respective Air Form or Water Form traits, it deals (1d10) fire damage in addition to any other effects. Plus, both types of elementals’ slam attacks deal an additional (2d6) fire damage on a hit, and the elementals’ respective Whirlwind and Whelm attacks deal an additional (2d6) fire damage against those who fail their saving throws.
  Elementals aren’t known for their Intelligence. They attack the nearest creature they can. The Water Elementals will try to Whelm opponents and drag them back into the scalding water. The air elementals seek to catch as many characters as it can with their Whirlwind attacking, potentially tossing the characters into the water as well.

3.

• Earthquakes: Small earthquakes are common. Once every 1d12 + 3 minutes, a tremor occurs. When a tremor occurs, roll 1d10. On a result of 1-7, the tremor is minor and the characters are unaffected. On a roll of 8-9, a major tremor occurs, lasting for 3 rounds. Each round the tremor continues, at the start of their turn, creatures on the ground must succeed on a DC 10 Dexterity saving throw or fall prone. In addition, rocks and debris tumble down the mountainside and from the ceiling of the cave. On initiative count 20, the sliding rocks make an attack roll against each creature that isn’t behind cover with a +3 bonus on the attack. If a creature is hit by rocks, it takes (2d6) bludgeoning damage. Finally, on a result of 10, a severe earthquake occurs and lasts for 5 rounds. The effects are the same as a major tremor, except the DC to avoid falling prone is 15 and the rocks hit with a +5, dealing (4d6) bludgeoning damage on a hit.
• Boiling Water: All of the water in the cave is boiling hot. Any creature that touches or attempts to wade through the water takes (2d6) fire damage.
• Lava and Magma: The biggest natural danger in the cave is the magma itself. The magma is very difficult to move through. Near the lava’s “shores” a creature at half speed through the lava. Towards the center of the magma pools, the lava can be as much as 30 feet deep, requiring that a creature swim its way through with a similar penalty to movement. Creatures of his cave suffer no penalty when swimming through magma and lava.
  When a creature touches the magma, it immediately takes (4d10) fire damage or (10d10) fire damage if it is completely submerged. If a creature remains within the magma, it takes an additional (10d10) fire damage at the start of each of its turns. Any flammable, nonmagical object that the creature is wearing or carrying is immediately destroyed by the magma. Metal items are also quickly destroyed by the magma’s intense heat. A weapon takes a permanent and cumulative -3 penalty to damage rolls as long as it is submerged in the magma. If its penalty drops to -5 or less, it is destroyed. Nonmagical ammunition made of metal that hits the lava is destroyed on contact. Nonmagical armor worn by a creature submerged in lava takes a permanent and cumulative -3 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10 or less.
  A creature whose hit points are reduced to 0 from the magma is completely dissolved. The creature can be restored to life only by means of a true resurrection or wish spell.
  The lava exudes extreme heat as well. Checks made to avoid exhaustion due to Extreme Heat start at DC 10 when within 30 feet of lava. And a creature that starts its turn within 5 feet of lava automatically takes (2d6) fire damage. Furthermore, flammable objects in the same range that aren’t being worn or carried ignite.
  The creatures immune to fire that live in the cave use the lava to their advantage. Fire immune creatures will hide in the lava, which offers full cover, then work to push those that aren’t immune to it into it.
• Tunnels and Ledges: The tunnels and ledges surrounding the magma lake are traversed only by the kobolds that toil there. Most are cowardly, and keep their distance from danger, although, one shouldn’t put it past them to attempt to push characters into the magma.
  The fractured path can be traversed with successful jumps, although there is always a 10% chance that one of the stones sinks under the weight of a creature (even if it’s been used by another creature). If the creature is large, the chance increases to 30%. When a stone sinks, the creature is instantly subjected to the effects of the magma (see above).
• A Red Dragon’s Lair: Red dragons lair in high mountains or hills, dwelling in caverns under snow-capped peaks, or within the deep halls of abandoned mines and dwarven strongholds. Caves with volcanic or geothermal activity are the most highly prized red dragon lairs, creating hazards that hinder intruders and letting searing heat and volcanic gases wash over a dragon as it sleeps. Lair actions start in this chamber.

4.

• Red Dragon Wyrmling wander around the cave and swim in the magma lake. If there is a danger, the children  go to the hoard room where they hide. The wyrmlings have black and red scales with light.
• 1d4 of Red Dragon Wyrmling.

5.

Loot

• Sacrificial Dagger of Tyr 
• Runic Gate Stone - Muspelheim 
• 6d20+100 copper
• 4d20+100 silver
• 2d20+100 gold
• 1d20 Garnet Red 
• 1d20 Ruby 
• 1d20 Sunstone 
• 1d20 Tiger's Eye 
• 1d10 Adamantine Ingot 
• 1d10 Gold Ring 
• 1d10 Silver Ring 
• 1d10 Silver Bracelet 
• 1d4 Silver Goblet 
• 1d4 Silver Bowl 

Earthquakes

• Small earthquakes are common. Once every 1d12 + 3 minutes, a tremor occurs. When a tremor occurs, roll 1d10. On a result of 1-7, the tremor is minor and the characters are unaffected. On a roll of 8-9, a major tremor occurs, lasting for 3 rounds. Each round the tremor continues, at the start of their turn, creatures on the ground must succeed on a DC 10 Dexterity saving throw or fall prone. In addition, rocks and debris tumble down the mountainside and from the ceiling of the cave. On initiative count 20, the sliding rocks make an attack roll against each creature that isn’t behind cover with a +3 bonus on the attack. If a creature is hit by rocks, it takes (2d6) bludgeoning damage. Finally, on a result of 10, a severe earthquake occurs and lasts for 5 rounds. The effects are the same as a major tremor, except the DC to avoid falling prone is 15 and the rocks hit with a +5, dealing (4d6) bludgeoning damage on a hit.

Jumping

• Your Strength determines how far you can jump.
• Long Jump. When you make a long jump, you cover a number of feet up to your Strength score if you move at least 10 feet on foot immediately before the jump. When you make a standing long jump, you can leap only half that distance. Either way, each foot you clear on the jump costs a foot of movement.
• This rule assumes that the height of your jump doesn't matter, such as a jump across a stream or chasm. At your GM's option, you must succeed on a DC 10 Strength (Athletics) check to clear a low obstacle (no taller than a quarter of the jump's distance), such as a hedge or low wall. Otherwise, you hit it.
• When you land in difficult terrain, you must succeed on a DC 10 Dexterity (Acrobatics) check to land on your feet. Otherwise, you land prone.
• High Jump. When you make a high jump, you leap into the air a number of feet equal to 3 + your Strength modifier if you move at least 10 feet on foot immediately before the jump. When you make a standing high jump, you can jump only half that distance. Either way, each foot you clear on the jump costs a foot of movement. In some circumstances, your GM might allow you to make a Strength (Athletics) check to jump higher than you normally can.
• You can extend your arms half your height above yourself during the jump. Thus, you can reach above you a distance equal to the height of the jump plus 1 ½ times your height.

Creatures

• Kobold
• Steam Elemental
• Water Elemental
• Ancient Red Dragon 
• Red Dragon Wyrmling 

Ore & Gems

• Blue: Lyrium Dust
• Red: Red Lyrium Dust
• Rock: Iron Ore, Coal Ore, Mithral Ore, Obsidian Ore, Ebony Ore, Adamantine Ore, Diamond Brown, Garnet Red, Ruby , Sunstone, Tiger's Eye

Type

Cave System

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:

• Magma erupts from a point on the ground the dragon can see within 120 feet of it, creating a 20-foot-high, 5-foot-radius geyser. Each creature in the geyser’s area must make a DC 15 Dexterity saving throw, taking (6d6) fire damage on a failed save, or half as much damage on a successful one.
• A tremor shakes the lair in a 60-foot radius around the dragon. Each creature other than the dragon on the ground in that area must succeed on a DC 15 Dexterity saving throw or be knocked prone.
• Volcanic gases form a cloud in a 20-foot-radius sphere centered on a point the dragon can see within 120 feet of it. The sphere spreads around corners, and its area is lightly obscured. It lasts until initiative count 20 on the next round. Each creature that starts its turn in the cloud must succeed on a DC 13 Constitution saving throw or be poisoned until the end of its turn. While poisoned in this way, a creature is incapacitated.