Kylem is a plane from Magic: The Gathering, introduced in the supplemental set Battlebond, which was a set dedicated to Two-Headed Giant draft. It is this plane that introduced us to Will and Rowan Kenrith, the planeswalking duo from Eldraine. This plane also introduced the Azra, which are basically just Tieflings without tails. They even have a handwaved away vaguely demonic ancestry, just like their main inspiration. The main mechanic of the set is the Partner keyword, that lets target player search their deck for an accompanying partner card, and put them into their hand. While it was intended to be drafted, they did have an emphasis on EDH, with many new cards and reprints in the set being perfectly tailored for the format.
The plane itself is, by the creator's own admission, not very fleshed out and made specifically for Battlebond. It can be best described as the plane of eSports and MMORPGs. Competitors from across the Multiverse come to Valor's Reach to compete in non-lethal two-on-two combat for fame and glory. People who fight in the arena very specifically style their hair, weapons, and clothing with outlandish colors and ridiculous styles to catch the eyes of onlookers and sponsors alike. The arena pushes competitors to not only win, but to win with style and bravado, with the arena having many hazards to enforce aggressive combat. Said obstacles include, but are not limited to: sudden flash floods, giant lava pits, twin-spell bonus leylines, magma worms, and 10/8 raid boss worms with glowing weak-points. For the visitor who doesn't want to just fight, Valor's Reach offers luxurious accommodations, a well-stocked marketplace, and glorious vistas that make it the prime tourist spot for planeswalkers.
There is also a mobile game that used to be called Valor's Reach (but is now known as Magic: Spellslingers) published by WoTC that takes place on Kylem. It's mostly notable for its... interesting take on famous planeswalker designs.
|Settings of Magic: The Gathering|
|Pre-revisionist:|| First Magic Sets - First Urza Block - Arabian Nights |
Legends - Homelands - Ice Age - Mirage
|Weatherlight Saga:|| Portal Starter Sets - Second Urza Block |
Tempest Block - Masques Block - Invasion Block
|Post-Weatherlight:||Otaria Block - Mirrodin - Kamigawa - Ravnica - Time Spiral|
|After the Mending:|| Lorwyn - Alara - Zendikar - New Phyrexia |
Innistrad - Return to Ravnica - Theros - Tarkir - Eldraine - Ikoria
|Two-Block Paradigm:||Kaladesh - Amonkhet - Ixalan|
|Never in a standard set:||Fiora (Where the Conspiracy sets take place) - Kylem (Battlebond)|