Going into a little bit of mechanics
There are general stages of dragon lifecycles.
Egg - Not aged as they are unhatched.
Wyrmling - >~6
Adolescent - ~6-~30
Adult - ~30-~150
Elder - ~150-~750
Ancient - ~750-~3750
Wyrm - ~3750-~18750
Great Wyrm - ~18750-~93750
After they 'exit' the Great Wyrm stage, they die in a matter of days. That is, unless they are directly 'spawned' from one of the dragon deities. In that case, they age exponentially slower in each stage, making them comparatively immortal.
For the purposes of the twilight stage, treat it as a second Great Wyrm stage for these 'demigod' dragons.
For the purposes of the 'cheated death' forms, repeat any of the bonuses from their current stage. They stop transitioning between stages but can still accumulate health. Though they do have other special rules.
For the purposes of the dragon deities, I simply consider them to be a 'Cheated Death Twilight Great Wyrm' with an additional Great Wyrm bonus.
Now, onto mechanics. Health is the only one that is strictly related to age and it uses my favorite mathematical expression bc it can. (This is the godbound system, bear that in mind) (n*(n+1))/2. Where n is the number of hit die they have, and thus, the result is their age in years.
The AC of an Egg is 8. Each stage they are afterwards decrease their AC by 2.
The saves starts at 10 and decreases by 1 each stage.
The morale starts at 8 and increases by 1 each stage.
They possess claw, tail, and bite attacks. They have a -2 to hit and damage and start out dealing 1d2 damage as an Egg. Each stage afterward increases the bonus to hit and damage by 1. It also alternates increasing the die number and die size. The Wyrm and Great Wyrm stages increase both rather than one (ending at 6d12). These attacks have an initial range of 0ft., it increases to 5ft. at the Wyrmling stage and increases the range by 5ft. each stage after adult. The Ancient, Wyrm, and Great Wyrm stages additionally increases the range by 5ft.
They possess a wing attack (technically an ability). This attack inflicts an evasion or hardiness save on every target in a cone. On a failure, they take the same damage they would from a claw attack, except the initial die size is 1d1 and they (the ones who failed) are pushed a number of feet away from the dragon. The distance they are pushed is initially 0ft. and increased by 5ft. each stage. The range of this cone is initially 0ft. but is increased by 15ft. each stage. The size of this cone's opening is increased by 5ft. every two stages, initially starting at 0ft. The Elder, Ancient, Wyrm, and Great Wyrm stages additionally increases the opening by 5ft. The Wyrm and Great Wyrm stages additionally increases the range by 15ft. each.
They may commit effort to move up to 5ft. per stage they are.
Initially, they possess one attack per attack action, gaining an additional attack every two stages.
The Great Wyrm stage gains an additional attack per action.
Initially, they possess one action per turn, gaining an additional action every three stages.
The Great Wyrm stage gains an additional action.
They gain 15ft. of movement every stage, initially possessing 15ft. as an egg. Yes, the egg can and will move around if the dragon inside feels threatened.
(n*(n-1)/2)*15 ft., where n is the stage of the dragon, as it's flying speed.
Innate Effort and Influence
Initially, they possess one effort, gaining an additional effort every stage.
Initially, they possess no influence, gaining an additional influence every two stages.
The dragon may commit effort to emit an aura out (n*(n-1)/2)*5 ft. where n is the stage of the dragon. This aura causes any non-draconic lesser foes within to roll for morale at the start of their turns, effected by existential fear on failure. This morale roll has an additional -1 for every two stages the dragon is.
The dragon can commit additional effort to this ability to grant the rolls an additional -1.
The dragon may commit effort for the scene to exhale a devastating blast of energy. A save is required for these breath weapons, either to avoid their effects or to halve the damage. Lesser foes make the save with a minus equal to the stage of the dragon. The types of dragons will specify any special effects or type of damage as well as what type of save that is required.
Damaging breath weapons initially deal 0d0 straight damage (yes, straight). Both the number and size of the die increasing with every stage (ending at 8d12). Because I can, I will specify the 'chromatic damage bonus', which is twice the number of dice. However, a number of the chromatic breaths have alternatives to the damage bonus as specified by their type.
With a few exceptions, all breath weapons can be exhaled as either a cone or a line, forcing all creatures within the area of effect to make the appropriate save.
A cone will affect out to (n*(n-1)/2)*20 ft., where n is the stage of the dragon. With an initial opening of 0ft. This increases by 5ft. every two stages. It is additionally increased by 5ft. in the Ancient, Wyrm, and Great Wyrm stages.
A line will affect out to (n*(n-1)/2)*60 ft., where n is the stage of the dragon. With an initial width of 0ft. This increases by 5ft. every two stages. It is additionally increased by 5ft. in the Ancient, Wyrm, and Great Wyrm stages.
It should be noted that the creation of a dragon's breath is magical in nature, but not the effects of the breath itself.
Because, for no other reason than I like even square tokens, they start out as a 05x0.5 token.
Increasing to a 1x1 in Wyrmling.
Increasing to 2x2 in Adolescent.
Increasing to 4x4 in Adult.
Increasing to 7x7 in Elder.
Increasing to 11x11 in Ancient.
Increasing to 16x16 in Wyrm.
Increasing to 22x22 in Great Wyrm.
(For the purposes of a token map where each space is 5ft.x5ft.)
The dragon can commit effort in order to change their appearance into another animal. Proportional in age to the chosen animal and in some way colored by the type of dragon. For example, irises like sapphires for a sapphire dragon, black hair for a black dragon, or golden skin for a gold dragon. The dragon types aren't limited to a specific coloration, for example, not all chromatic dragons color hair. Despite the change, they lose no access to any of their draconic capacities, they don't age like their new race, and they don't even lose the ability to speak. This does grant them the ability to sire half-dragons with the race they have changed into, which, can be quite the shock for many. Dragons can likewise use this to simply decrease their draconic bulk, up to half the number of stages they have rounded down.
For the purposes of half-dragons, they lack this feature. Double or halve the other features as appropriate. For example, double the age for the same number of hit points. For the purposes of lifespan, average the dragon's to the other parent's race. This will usually create a far longer-lived member of the race than usual, but a far shorter-lived than normal dragon. Even though they lack this shapechanging trait, they are capable of generating more 'quarter' and 'eighth' and 'sixteenth' and so on. Repeating this process each time, until the differences are near indistinguishable from the standard of the race.
For proportional apparent ages, I will give human age range examples.
Wyrmling - Ages 1 - 12
Adolescent - Ages 13 - 19
Adult - Ages 20 - 29
Elder - Ages 30 - 39
Ancient - Ages 40 - 49
Wyrm - Ages 50 - 59
Great Wyrm - Ages 60 - 69
Twilight - Ages 70+
For the purposes of damage types dealt by the dragon's breath weapon, for each stage of the dragon, they take 24 less damage (yes, damage, not 'lower the damage roll') (a total reduction of 192 at Great Wyrm). No, I did not make them outright immune, see half-dragon for the reasoning there.
As for 'statuses' granted by breath weapons, saves to resist such effects receive a +4 to the roll per stage.
They are capable of resisting the mystical qualities of their lineage with a +2 to the roll per stage.
Due to dragons being an immutable force of the universe, impossible changes related to a dragon gain an additional resistance of +3 per stage, improbable changes gain an additional resistance of +2 per stage, and probable changes gain an additional resistance of +1 per stage. That is assuming that they are opposed to the change, and no, they can't leverage this trait to make changes easier.
Dragons can innately speak, read, and write Draconic, the language of dragons. There are naturally thirty-four dialects (one 'true' dialect, one for every lineage, and one for every type of true dragon), though dragons can utilize any of them if they wish.
Dragons, due to their innate connection to the realm they are in, can speak, read, and write the most predominant language of the area. However, they do not have any special ability to retain this knowledge after leaving the area. Many dragons, if they actually care about the native languages, will take measures to truly learn them rather than relying on this ability.
For the purposes of their senses, they are always considered to be worthy foes. They are even allowed rolls against things such as the word of Deception, although they make such rolls with a -12.
For rolls related to vision, they get +2 per stage after Wyrmling.
For rolls related to olfactory or hearing, they get +1 per stage after Wyrmling.
They have tremorsense out 10ft. per stage and blindsight out 5ft. per stage.
The dragon may commit effort to make their bite, tail, or claw attacks count as magical for the purposes of overcoming resistances and immunities.
They may commit an effort to infuse a small portion of their breath weapon(s) into their bite attacks. At the Ancient stage and beyond, this infusion is permanent. For the purposes of damaging breath weapons, it is simply 1d2 additional damage per stage of the dragon. Wyrms and Great Wyrms increase the die size by one. Most infusions have additional effects which will be specified in the dragon type.
