Unaging
Dymarnians exist as they are and don't change over time.
Tongues
Dymarnians understand all languages. When a Dymarnian speaks, anyone capable of speech can understand. The sounds they make when speaking in tongues sound other-worldly and impossible for mortals to replicate.
Summon
When you speak the True Name of a Dymarnian, you are attempting to summon them. They can choose to go, or they can attempt to refuse the call, which is a battle of wills. When you summon them, they disappear where they are and reappear where you called them. There are Conarite priests who have developed rituals to force the summoning to work. They always hear when you speak their True Name, and anything you say for a few seconds after.
Darkvision
Dymarnians are always in the light of the moons, Katergis and Synigora. As long as neither of them is in its New Moon phase, Dymarnians can see in the dark. They do this by calling the moonlight to reflect off of their eyes, causing them to glow slightly. For most, this is not enough to light the way for those who struggle in the dark, but it's enough to make them easy to spot. The effectiveness of this is dependent on the phases of the moons. If both moons are in the New phase, then Dymarnians actually all worse-off than humans in the dark!
Hardy Flesh
Dymarnians do not need to eat, sleep, or breathe. They can ingest things and enjoy the taste, but it doesn't physically do anything for them. They are immune to most poisons and don't get sick. When damaged, their bodies regenerate quickly, though they can still be killed with significant damage to their heart or head. They may have other weaknesses, but this depends on their type (a demon of fire may be hurt by water).
Animals
Although Dymarnians often appear human when they choose to, animals can tell that something isn't quite the same. For some, this means animals love them, but for others, this means animals fear them.
Divine Magic
Dymarnians often have some kind of other power, which is considered Divine Magic. They cannot attune but they can use tinkered objects. Most Dymarnians summon wings or make other changes to make their physical form more powerful. Many of them can also change their form to look human.