This is part of a series! Go here to see the other entries.
Adamantine dragons are the first metallics we’ll cover. I finally found a wiki with publication histories for monsters, so I can say that that they first appeared in a Monstrous Compendium for AD&D 2nd Edition, and in a Dragon article for 3.x. This means they had a minor presence in the game until their first proper Monster Manual appearance here.
Adamantine dragons like to lair in huge underground caverns, and can be found in any sort of climate. They consider everyone else living in their claimed territory to be their subjects, from whom they demand loyalty, respect, and tribute. The flip-side of this is that adamantine dragons feel a genuine sense of noblesse oblige towards these subjects, and will protect them with all their might.
Their claws and fangs are made of their titular metal, so their attacks slice through armor as if it wasn’t there. Their roars are powerful, and their breath weapon is a focused sonic attack. In combat, they’re cool-headed and tactical. If alone, they try to isolate weaker foes and focus fire on them. If accompanied by allies, they’ll charge to the front line and attract the brunt of enemy attacks to allow their allies more opportunities to damage the opposition.
As usual, we get stat blocks representing four age categories: Young, Adult, Elder, and Ancient. All are Natural Magical Beasts with the Dragon keyword. All stat blocks are Unaligned.
Adamantine dragons start at size Large, growing to Huge at Elder and Gargantuan at Ancient. They have trained Perception, Darkvision, and Thunder Resistance that starts at 15 and goes up by 5 on each subsequent age category. Their ground speed starts at 6 and rises to 8 on Adult and older. Their flight speed starts at 8 and rises to 10 on Adult and 12 on Ancient. They also have Overland Flight 15, which is the speed you use when calculating how much distance they cover over extended times.
Young Adamantine Dragon
This is a Level 7 Solo Soldier with 332 HP and the traits described above. Its basic attacks are a bite and a claw, both of which target Reflex instead of AC because they’re adamantine. The bite is a little stronger, Double Attack allows the dragon to claw twice in a single action.
Their Breath Weapon (close blast 5 vs. Fortitude; recharge 5-6) does thunder damage and knocks the targets prone on a hit. It replaces the usual “half damage on a miss” with a much more interesting Effect: at the start of the dragon’s next turn, it gives a thunderous roar that deals automatic thunder damage to everyone in a close burst 3.
Bloodied Breath and Frightful Presence are here, and they work as outlined in the intro.
Wing Buffet (melee 2 vs. Fortitude) is a reaction that triggers when an enemy enters or leaves an adjacent square. On a hit it deals light physical damage and knocks prone. This is better than a standard opportunity attack because it also triggers on a shift or other forms or movement.
Adult Adamantine Dragon
Adults are Level 14 Solo Soldiers with 564 HP. Their numbers are of course all larger, but they are almost identical to young dragons in what they can do.
There have been a few additions: the bite now also inflicts ongoing damage (save ends), and Double Attack is replaced by Draconic Fury, which allows them to make three claw attacks and bite a different target in a single action.
Elder Adamantine Dragon
Elders are Level 21 Solo Soldiers with 796 HP. They have everything adults have, with a few additions:
Their Draconic Fury gains another claw attack, for a total of four claws and a bite. They also gain a new attack named Painful Resonance (Ranged 20 vs. Fortitude; minor action; recharge 6) that inflicts ongoing thunder damage and dazes (save ends). Since this is a minor action, it can be used in the same turn as Draconic Fury.
Ancient Adamantine Dragon
Ancients are Level 28 Solo Soldiers with 1020 HP. This puts makes them a match for a pair of primordial colossi. They have everything elders have, plus their melee reach increases to 4 and the area of their Breath Weapon’s follow-up roar increases to 5.
They also gain a new trait named Bloodied Resilience, which gives them Resist 10 to all damage while they are bloodied.
Sample Encounters and Final Impressions
The book doesn’t even pretend you’re going to fight these solos by themselves, though that of course is an option depending on what you want. Since adamantine dragons place themselves in the front line, they favor allies who can benefit from the distraction to rain ranged damage or control upon the enemy, or give the PCs the run-around and hit their squishies. And they’re going to think of party composition in these terms, since they’re tacticians.
The sample encounter is level 15, an adult adamantine dragon and 2 banshrae warriors.