Runeterra (meaning magic earth) is a plane of existence composed of the physical realm: an oblate spheroid planet[1] and the Spirit Realm. It is also the fictional world where most of the lore of the League of Legends intellectual property takes place.
Runeterra is part of the larger Runeterra Prime universe. The currently known continents the planet comprises are Valoran and Shurima. It also boasts several large bodies of water, such as the currently known 18 Seas (like the Conqueror's Sea and the Guardian's Sea), and 2 Oceans with several archipelagos and islands around them (like Ionia, the Serpent Isles, and the Shadow Isles).
The planet orbits around a G-type star while a natural satellite moon orbits around the planet. Runeterra's sun and moon also even mirrored equivalents in the spirit realm.
Magic
Magic plays an important part in the history and formation of Runeterra, much like the meaning of the world's name. There are several types of magic that exist in the universe, primary and combined magics. The Void has no magic at all since it is nothingness.
Beings born or created with magical power have different levels of power. They are able to channel their innate magical power, though their level of control and mastering it varies between individuals. Magical power non-native to the individuals can still be accessed and channeled by using special techniques or magical artifacts.
Primary Magic
Currently there are 3 primary types of magic known:
Celestial: Magic coming from celestial concepts known as Aspects and world runes.
Elemental: Magic that allows the control of elemental power of the material realm. There are numerous base elemental magics, such as Magma, Nature, Water, Light, and Time. The people of Ixtal are known for mastering elemental magics. Chronomancy, or Time magic, is a form of elemental magic considered so advanced as to only be theoretical. Zilean and Ekko make use of this to manipulate the flow of time near them in different ways.
Ferromancy, or Metal magic, is a form of elemental magic that manipulates metals and metal alloys. It is also potent against revenants whose spirits are attached to their armors.
Light magic appears to encompass the ability to manipulate or create visible light and perhaps other parts of the electromagnetic spectrum. The full extent of it is unknown, but it has been shown to have protective qualities, the ability to create immense force, heat, and project light into the vision of even the blind. The illusory capabilities of this magic are unknown, though it is possible LeBlanc uses it this way.
Spirit: Magic coming from the spirit realm. One of its known traits is that it is able to distort reality, the perception of reality, and harness the energies of a soul. A demonic offshoot of spirit magic is Shadow, which is primarily used by the members of the Shadow Order and demons such as Nocturne.
Combined Magic
Primary types of magic can combine to become many other basic types of magic, of which, the following are known:
Ascended: Celestial and elemental magic; Pivotal in the creation of the Ascended. One of its abilities is to reshape physical forms, prolong lifespans, greatly empower and expand the base abilities of an individual, as well as create a connection between the Ascended and Aspects.
Hemomancy: Elemental and spirit magic; Largely used by the Darkin, later on by the members of the Crimson Circle. One of its abilities is to reshape physical forms, prolong lifespans, absorb life essence of a living being, as well as manipulate blood.
Hextech: Elemental and spirit magic combined with technology; Invented and largely used in Piltover and areas of Piltovan influence, Brackern crystals are integral in creating authentic Hextech devices. One of its abilities is to animate and/or empower technological devices as a fuel source, as well as prolong lifespans.
Runic: Celestial and elemental magic; Runic magic is often written down with special symbols known as words of power. One of its abilities is to empower the base abilities of an individual and prolong lifespans.
Will further explain as the story progresses...
Species
Runeterra has a large number of sapient species. These sapient species can range from being able to use primitive tools to one's advantage to god-like feats like forging literal stars. Some sentient species are monster-like and aggressive while others less aggressive or tame.
While most sentient species are animals, there are instances of plant based sentient species. Most known instances of non-sentient species are found with plants.
As rich and diverse as Runeterra is, not all species are well documented. From the Shuriman Jungles to the magic wilds of the Ionian Archipelago, known only by names or by visuals, these numerous species are an enigma.