As dragons grow, they gain in hit dice, hit points, ferocity and dangerous potential. Even the most immature of dragons make formidable opponents, while dragons of great experience are probably the most dangerous mortal beings in the world.
HatchlingsAt birth, a hatchling will be about 5% the full mass of an adult dragon. Thus, while a sturdy brass dragon would weigh about 3,500 lbs., a hatchling of the same species and form would weigh 175 lbs., or as big as a fully grown human. This calculation also gives the weight of the dragon's egg, not being something that can easily be moved. A hatchling is about 10% of a full-grown dragon's length.
A hatchling's hit dice will be only 1/4 that of an adult, always rounded down. The aforementioned brass dragon would have 7 hit dice as an adult, but only 1 hit die as a hatchling (and attack as such). Comparing hit points per die would show that the hatchling would have only 1d8 hit points.
Hatchlings will remain of this age for only a month after birth, before quickly morphing into yeuldings. They will emerge from the egg with claws and teeth, but with only bony stubs where their wings will someday be and only a short, not-yet-grown tail. The claws will cause 1-3 damage and the bite 1-6. The body of a hatchling is soft, so that this calculation should be used to determine its armor class: (x + 10)/2, where x is the armor class of an adult dragon, with all fractions rounded up. The brass dragon with an armor class of 2 would, as a hatchling, have an armor class of 6.
Hatchlings possess a breath weapon that will cause 1 hit point per hit die of their fully grown selves. The hatchling brass dragon in the example above will someday have 7 hit dice, so its breathweapon will cause 7 damage, 3 if a saving throw is made. The alchemical gland is immature, however, so that it will drain after only one use in 24 hours. As well, the effective range and volume is only one combat hex, or 5 feet.
YeuldingsA month after emerging from the egg, a hatchling will molt its outer skin and grow in a few days to yeulding size. During this time the dragon will be vulnerable and unable to defend itself, but typically the dragon will bury itself in mud or sand up to ten feet deep, sometimes finding these conditions at the bottom of a pool or pond. The adult dragon will usually be nearby and protective of the yeulding. Dragons molt in this manner only once in their lives.
Once the yeulding passes through this period of growth, it will be 20% the full mass of an adult dragon. While a sturdy brass dragon would weigh 3,500 lbs., a yeulding of the same species and form would weigh 700 lbs. A yeulding is about 30-40% of an adult dragon's length. It's hit dice will be 1/2 that of an adult, always rounded down. Thus, whereas a sturdy adult brass dragon has 7 hit dice, a similar yeulding has 3 hit dice. A brass dragon yeulding of this form would have 3d10 hit points.
Yeuldings will remain of this age for about four years, before experiencing a radical growth spurt. Yeuldings will have wings that have sprouted and their tails will lengthen; however, yeuldings cannot fly and the tail is not flexible enough to be used as a weapon. The scales of a yeulding's body will be as hard as that of an adult, so that they possess the same armor class as an adult dragon. The damage from a yeulding's bite and claws will be 1/2 that of an adult.
Yeuldings possess a breath weapon that will cause 2 hit points per hit die of their fully grown selves. The yeulding brass dragon in the example above will someday have 7 hit dice, so its breath weapon will cause 14 damage, 7 if a saving throw is made. The alchemical gland is yet immature, however, so that it will drain after only two uses in 24 hours. The effective range and volume is reduced also, to an area of 3 combat hexes, straight out or sprayed in front of the dragon's mouth in a shortened cloud.
Young DragonsThe growth spurt of a yeulding to a young dragon is a dramatic shifting and adjusting of the dragon's outer appendages, happening over a period of 2-4 months. The limbs extend, the wings grow out and the tail becomes flexible and longer, while the dragon's neck lengthens, enabling it more control over the placement of its breath weapon. The bones of the dragon can be literally heard as they grow, a cracking, sometimes grinding sound. In overall mass, the dragon does not increase that much ~ only to 40% of the full mass of an adult dragon. Throughout the process, the dragon will be able to protect itself and should be considered to be no longer a yeulding once the process has passed the second month.
Young dragons are about 75% of an adult dragon's length. It will have the hit dice of a full-grown adult, less 2. A young, sturdy brass dragon would have 5 HD. At 40% of the adult dragon's mass, it would weigh about 1,400 lbs. and have 5d12 hit points. Young dragons will have the full use of their wings for flying and of their tails as weapons, but as they are quite clumsy they have not yet learned how to maintain a buffeting rhythm nor how to rake with their back claws. The damage from a young dragon's bite, claws and tail will be 3/4 that of an adult.
Young dragons will also have reached a weight and size where they cause incidental damage.
Young dragons possess a breath weapon that will cause 3 hit points per die of their fully grown selves. A young brass dragon of the example above would someday have 7 HD, so its breath weapon will cause 21 damage, 10 if a saving throw is made. The alchemical gland is yet immature, however, so that it will drain after only two uses in 24 hours. The effective range and volume is reduced also, to half the area of effect of an adult dragon.
Young dragons will not mature until they reach an age of 15-18 years.
Near-Grown DragonsAfter 13 years of age, a young dragon's overall body and bulk will begin to mature, as the bones harden and gain weight, as the dragon's spines and ridges stiffen and increase the dragon's protection against hand-to-hand attack. Beginning at 15 years of age, some dragons must be considered nearly grown to adulthood; no dragon that is 18 years of age or older can be considered young.
Nearly grown dragons will have 80% of the full mass of an adult dragon and be equal in length. Thus, they are hard to distinguish from adults. Near-grown dragons will attack with the full hit dice of their adult dragon peers and cause damage with their bite, claws and tail that is equal to an adult dragon. They will be able to buffet with their wings (for 1-4 damage) but will, as yet, be unable to rake with their back claws.
Because of the spines and ridges on a near-grown dragon's body, the amount of incidental damage caused is double-normal, or potentially 1 damage per 500 lbs. of the dragon's weight.
Near-grown dragons possess a breath weapon that will cause 4 damage per hit die. A near-grown sturdy brass dragon's breath weapon would cause 28 damage, 14 if saving throw is made. The alchemical gland is still that of a young dragon, however, so that it will drain after only two uses in 24 hours. The effective range and volume is reduced also, to half the area of effect of an adult dragon.
A prime difference between near-grown dragons and adult dragons is that the former cannot mate or lay eggs. As such, being of full size but not yet with the responsibility of a family, near-grown dragons are the most likely to be encountered as solitary dragons in the wide world. Because they are only 15 to 40 years of age, it is the behaviour of near-grown dragons that has often created the myths and false beliefs about dragons.
Adult DragonsOnce maturing to adult, typically something that comes about gradually between the age of 35 and 40, a dragon has reached the pinnacle of its physical characteristics. It will weigh approximately 500 lbs. per hit die, attack ably with bite, claws (including the ability to rake with its back claws), tail and with buffeting wings. The amount of incidental damage caused by the dragon is double-normal, or potentially 1 damage per 500 lbs. of the dragon's weight (or coincidentally 1 h.p. per HD).
An adult's breath weapon will cause 5 damage per hit die. The alchemical gland that produces the substance of the dragon's breath will sustain three uses in 24 hours and will reach to the full range and area of effect of the dragon's power.
Adult dragons will mate for life. They will remain adults until reaching 80 to 100 years of age, and during that time will raise a brood every 12 years, typically in the late spring or at the start of the wet season, so that hatchlings will be able to molt into yeuldings when mud and wet sand is available. Dragons will fly up to 10,000 miles to isolated areas of mud and sand, often choosing the thickness of jungles, muskeg bogs, isolated island atolls or deep deserts (where some yeuldings will molt under sand dunes).
Broods will consist of 1 to 4 hatchlings, of which one in four will typically die during the molting stage for reasons that are generally unknown. Population growth can become unstable for a time, but typically dragons are removed from the prime material plane to the outer planes for a variety of reasons; typically, a pair of mated adults are chosen to breed elsewhere. This helps reduce the number of dragons being bred on Earth.
Old, Very Old and Ancient DragonsOnce reaching an age where dragon pairs become infertile, anywhere from 80 to 100 years of age, they will settle in a permanent lair where they may remain the rest of their lives. This will often not be the same location where they gave birth, as that was founded on the strange growth cycle of dragons and not necessarily with a desire to protect themselves. Old dragons will prefer deep caves inside mountains of every climate, large impassable swamp lands, the top ridge of ocean trenches or crevices of great size amidst glaciers, depending on the species of dragon.
While they do not become physically stronger or increase their hit dice, once old dragons settle they will being to accumulate energy levels, similar to the levels that characters gain as they accumulate experience. Dragons gain knowledge directly through the earth, through a meditation that is enabled by the magical design of their minds, enabling them to grow in power as clerics or mages, and most commonly as fighters. Typically, an old dragon will have gained their first level within 5 years of seclusion. Thereafter, they will gain a new level every 25-30 years, gaining hit points, spells, sage abilities and so on as they accumulate. These gains are indistinguishable from the levels a character will gain, except that dragons are able to discharge the spells they possess at will, without any requirement for the spells to be cast first.
Eventually, a dragon-fighter's skill will increase the number of attacks that a dragon will have each round, or increase the dragon's THAC0. In terms of sage abilities, old dragons tend to focus on general knowledge rather than applied abilities, since they expect to spend decades in contemplation, only occasionally rising to a discussion with other dragons of their age.
Old dragons, because of their experience and improved ability to target with their breath weapons, will cause 6 damage per hit die with their breath weapons. Very old dragons will cause 7 damage per hit die and ancient dragons will cause 8 damage. This is the primary physical difference, since the number of hit dice will not increase after the dragon becomes an adult, nor will the amount of damage the dragon is able to do with their physical bodies.
Typically, old dragons will become very old once they reach the 5th level of experience (between 160 and 195 total years of age). Very old dragons will become ancient once reaching the 9th level of experience (between 260 and 315 years of age). The maximum age of ancient dragons is unknown, but it is believed that they will pass away, if not discovered and killed, before they reach 600 years of age.