The Burned Realm is the barren ash-filled land of the dead, where the dead exist in their afterlife and time moves strangely and almost nothing living can be found. It is possible to travel there with Ash Magic. Naturally-ocurring gates there have been found too. Blood Magic and Wind Magic are weaker in the Burned Realm than elsewhere.
The Burned Realm may or may not mirror the real world's geography. There seem to be analogues to the Three Rivers, the Great Forest, and the world's major cities. They do not seem to be perfect one-to-one replicas though.
There may be a hard-copy map of the Burned Realm knocking about somewhere in the LARP folder from the Journey To The Burned Realm LARP, but it's an IC document (and so may be inaccurate.)
Important features are:
The Woods of the Lost
The Tower of Heroes, where great heroes go after death.
Silverfall, a dead city destroyed by the Binding War, whose inhabitants are under possession by a hive-mind entity named the Soldier.
The Rose Gardens, including
The Garden of Follies, which fell into the Shattered Plain and whose replacement has only started to regrow.
The Garden of Perfidy, housing those who died of treachery. Also fell in to the Shattered Plain but was regrown with the help of Harriet Pinter.
The Garden of Grey Roses, which houses those who died of old age.
The Garden of White Roses, which houses the dead by love.
The River of Follies, which flows with ash
The House Of The Gods, where gods go when they die.
(Raising the Saint)
Adventurers travel to the Burned Realm to gather ingredients necessary to empower replacement Gardeners to act in the Lord of the Gardens' stead. Galina Shaw becomes the Lord of White Roses, the former gardener of Red Roses becomes the Lord of his garden and the
former gardener of Black roses is replaced by the man who once stabbed the Lord of the Gardens (see the fiction page: How the Rattle Prince Stole Immortality) (How Does Your Garden Grow?, In The Shadow Of The Sun)
(Once Upon A Time In The East)
The Grey Templar, Galina Shaw, a former Ash Priest in service to the Necromancer at Three Rivers, abandons her loyalty to the Necromancer and chooses to serve the Burned Lords. She becomes a new Gardener in the Rose Gardens. She later ascends to become the Lord of White Roses. (Last Orders)
The Lord of the Faithful summons several dead adventurers on a mission to fix a problem created by Selena in the Burned Realm. (Things to do in the Burned Realm When You're Dead)
A party of adventurers pursue the Necromancer at Three Rivers through the Burned Realm, where he has created seven Defiers, beings with which he intends to replace the Burned Lords. They defeat his Defiers and then him. (Even Death May Die)
Some adventurers enter the Burned Realm. They visit the dead Lord of the Gardens in the House of the Gods and heal the Lord of the Faithful and the Lord of the House of Gods of their glass infestations, using Gardens' alchemy and amputation respectively. They steal a dagger from the Lord of the House of Gods and slay a glass monstrosity that planned to attack the Lord of Silent Voices. (Faith and the Fallen)
Selena Curiana and minions pursue the Lord of the Gardens into the Burned Realm and kill him. The Rattle Prince intervenes to ensure that the gardener of Grey Roses becomes a new goddess to watch over the dead by age called the Lord of Grey Roses. (The Horror In The Garden)
Toquell Velasquez and minions travel to the Burned Realm via an existing, permanent Burning Gate in the Breathing Isles in order to steal the Maiden of Tempests from the House of the Gods. They don't so much steal her as set her free. (Death & The Maiden)
The Necromancer At Three Rivers sets many undead free from the Burned Realm; adventurers travel to the Burned Realm to put them back. (Journey To The Burned Realm)