Ghost Dragon

(From Fizban's Treasury of Dragons - 2021):

A dragon’s attachment to a hoard can be strong enough to bind the dragon’s spirit to existence after death. Such a ghost dragon haunts the hoard, often forming an attachment to a single priceless object that becomes the focus of the ghost dragon’s Undead existence.

A ghost dragon is a translucent and incorporeal version of the original dragon. Though its breath weapon resembles ghostly flames, lightning, or acid, it carries an otherworldly curse. The breath’s shadowy mist can induce waking nightmares.

(From 2nd Edition AD&D Monstrous Manual - 1991):

A ghost dragon is a sinister-looking, semi-transparent figure. It resembles whatever dragon type it was in life. All ghost dragons are a swirling murky gray, and they always speak in quiet whispers.

A ghost dragon is created when an ancient dragon is slain and its hoard looted. In many cases, the dragon died defending its hoard and home. The tie between a dragon and its hoard, however, goes far beyond mere human greed or dwarven avarice. The dragon will haunt its former lair until it manages to accumulate enough treasure to equal the value of its vanished wealth; then it will depart and rest in peace.

Ghost dragons never stir from their lairs. They are less belligerent than their living kin, but more obsessive. In many ways they resemble revenants more than true ghosts, except that they have no interest in revenge. All a ghost dragon thinks about is its treasure. Unfortunately for intruders, in the ghost dragon’s mind, any and all valuables brought into its lair fall into this category. Since a ghost dragon can find peace only if it succeeds in rebuilding its hoard, it will demand trespassers hand over any treasure they are carrying — gold, jewelry, magical items, etc. The creature will allow polite adventurers to keep 10% of their possessions (a procedure it calls “tithing”) and will answer questions they might have regarding neighboring monsters or events it knew about in its lifetime. Those who refuse to turn over their valuables are savagely attacked.

Combat: A ghost dragon has several different attack modes, and since it is an exceptionally intelligent creature, it will always choose the combination that will best achieve its goal. Ghost dragons have a fear aura far more dangerous than that of their living counterparts. Victims of a ghost dragon’s aura must make two saving throws, both at a -4 penalty: one vs. petrification to avoid aging 10-30 (1d3x10) years, and a second vs. spell to avoid cowering in terror for a full turn (10 rounds). Note that the aura affects all in the dragon’s lair at the time it appears, including beings normally immune to fear effects, such as paladins.

A ghost dragon never ambushes intruders; it uses its aura first to get their attention and give them a chance to hand over their wealth without a fight. If they refuse and attack the ghost dragon, try to leave, or (worse yet) attempt to steal some of its remaining treasure, it begins its assault. In addition to its aura, a ghost dragon has a claw/claw/bite/tail-slap sequence daunting to even the toughest warrior. Not only can it inflict up to 104 points of damage in a single round, but each successful hit requires the victim to make a saving throw vs. death magic or lose two levels to an energy drain. Further, the limb struck (determined randomly) is affected as if struck by the withering power of a staff of withering: It shrivels and becomes useless unless the victim successfully saves vs. spell.

The ghost dragon also has a breath weapon it can use three times before it must desist 12 rounds to renew its internal energies (at which time it can breathe three more times). The breath weapon is a cloud of gray mist 50-feet long, 40-feet wide, and 30-feet high that ages any creature caught in it as follows: humans, halflings, halfelves, most humanoids 1d100 years; dwarves 3d10�10 years; gnomes 6d10�10 years; and elves 1d100�10 years.

Ghost dragons are immune to all spells cast by nonethereal opponents and all weapons of less than +3 enchantment. They are immune to charm, sleep, hold, and all mind-control magic, even if the caster is on the Ethereal Plane. They cannot be turned or controlled by priests; they are also immune to holy water.

If a ghost dragon is killed by damage or magic, it simply reforms 48 hours later and resumes its attempts to build its hoard. Most adventurers who have encountered a ghost dragon have found out that it is better to give the creature what it wants. The experience point values for dealing with ghost dragons reflect its unusual nature.

The only way to lay a ghost dragon to rest permanently is by giving it treasure. Once it has gathered enough wealth to replace its lost hoard in gp value (it need not literally be the exact treasure the dragon hoarded while alive), it will whisper a quiet “thank you” and disappear forever, never to return to the Prime Material again, leaving the accumulated treasure behind for anyone who wants it.

Habitat/Society: Ghost dragons are solitary creatures haunting the desolate ruins of their empty lairs. They can be found anywhere a live dragon would secure its most prized possessions, but always in dark, underground, or indoor places. As intelligent creatures, they enjoy the occasional conversation with intruders, but never allow themselves to be talked out of the treasure they need. Since only the eldest dragons (ancient dragons) possess the will to continue to exist beyond death as ghost dragons, and since most ghost dragons spend centuries if not millennia in that state, they can be valuable sources of information about the past — for those adventurers willing to pay their price. It is rumored that living dragons sympathize with the anguish that the ghost dragons feel over their plundered wealth and often help their departed kin by sending potential treasure their way in the form of unwary adventurers.

Ecology: Like most incorporeal undead, ghost dragons play no part in the living world, nor do they need to eat or sleep. Ferocious predators in life, in death they completely drop out of the local ecology. They do, however, play a large part in the economy of the regions they inhabit, as their “tithing” of passing adventurers tends to deplete both cash and surplus magical items in those areas. (An enterprising DM can use a ghost dragon to curb runaway inflation in a campaign world.)

Of course, after a ghost dragon regains “its” treasure and passes on to its afterlife in the planes, all the above-mentioned treasure remains behind to taken again by those with the courage.