The Three Realms

• The Three Realms, consisting of Astra, Terra, and Umbra, make up a layered system that comprises the planet Earth, with Umbra as the innermost layer, Terra as the middle layer, and Astra as the outermost. Each realm has its own ecosystem of terrain, wildlife, and peoples, and are generally seperated from each other but do connect in specific ways and together form a cohesive whole.

Umbra

• Umbra is the realm below, a realm with no sky but glowing seas and rivers of magma. a land with a varied and unique landscape of large darkened cave complexes, bright magma floodlands, glass beaches, and unique blue vegetation built for absorbing the sparse light and nutrients of the magma below. the people of Umbra as well have uniquely evolved in their realm, often with a strong affinity towards shadow, stone, and fire magicks. Examples of Umbrans include Imps, Titans, and Draconians.
• Being within the planet, Umbra is the smallest of the three realms, has had a rather violent history of land wars both within the realm itself and attempting to claim parts of Terra, the realm between. though the realms have few natural connection points, Umbra does bubble up into Terra at volcanic sites, which serve as gateways between the realms. In the past, particularly large parties breaking into Terra through these sites have caused devastating eruptions. Incidents like these still happen today but are far calmer and less common, and a relative peace has settled between the realms.
• Several Umbrans now reside on Terra, though they often face prejudice from Terrans (especially Humans) and are frequently derided as "demons" or "monsters". some Umbrans have reclaimed these labels, but they remain a sore spot for many.

Terra

• Terra is the realm between, the surface of the planet, a realm with an abundance of water, nature, and life. Terra has no sway in the direction of light or shadow in particular. Terra's surface is extremely varied, but a majority is taken up by large oceans, and the above-water areas are lush with forests, and peppered with snow-covered peaks and tundras. The creatures and peoples of Terra often carry an affinity towards water, nature, or ice magicks, although some are more balanced, particularly Humans which have small but equal affinity in all elements. Other examples of Terrans include Merfolk, Faeries, and Yuki-onna.
• As the realm between, as well as the largest of the three, Terra is often the meeting place whenever the realms interact, be it war or peace. As such, it has a sizable population of both Umbrans and Astrans in addition to its native Terrans. Much of Terran history is influenced by the acts of particularly brazen Umbrans or Astrans wishing to exert their influence on the realm between, which is not to say the Terrans do not have plentiful culture and history of their own. The history of Terra is long and complicated, especially the in-fighting of various Human nations, so I will trust you to do your own research on this subject. [i.e. apply real world history knowledge LOL]
• Many Terrans have mixed feelings about the other two realms. Public opinion of Astrans is historically the better of the two, but peoples of both realms often face friction in Terran societies.

Astra

• Astra is the realm above, with the open sky above and sea of clouds below. The 'landmasses' of Astra are few and far between, and range from floating islands to dense thunderclouds to the backs of massive skyfaring creatures. The realm of Astra is without shade, so the flora and fauna of Astra are adapted to the near undending starlight, and often have a strong affinity towards light, air, and thunder magicks. Examples of Astrans include Angels, Harpies, and Great Serpents.
• The sparse and seperated nature of the lands of Astra lead to most Astrans requiring the capability of flight to venture beyond their home. Some attain this flight through wings or air-aspected magic. Others, typically larger creatures, travel the sea of clouds by virtue of having a high bouyancy to 'swim' among the denser cloud covers. Even with these capabilities, many societies on Astra are tight-knit isolationists who do not go out of their way to travel beyond their homelands.
• Wars among Astrans are relatively uncommon compared to the other two realms, but it is not without conflict, and Astrans have been known to interfere with Terran affairs, particularly egoistic Astrans who believe the other realms to be beneath them (in the non-literal sense).