The Verdant Fields of Arvandor was a notable layer of the Chaotic Good plane of Arborea in the Great Wheel cosmology of Dungeons & Dragons, as well as being a stand alone plane in the World Tree cosmology of the Forgotten Realms campaign setting of 3e. It was later a Dominion within the Astral Sea of the World Axis cosmology of 4e. In all incarnations it is the home of Corellon and Sehanine, as well as their servitors: the Seldarine but is also a common resting place for Avandra and Melora, who have a particular compatibility with Arvandor and its owners.
Arvandor takes the form of six large, steep islands covered in glorious fey forests, with its border islands forming an archipelago of dozens of smaller, but no less beautiful and verdant, isles. Many poets like to wax rhapsodic about its eternal beauty and the life of ease and luxury that comes to the ruesti - the Exalted chosen to dwell here. Such poets are typically humans or halflings who don't actually worship Corellon, or else they'd know they're talking out of their asses.
See, Arvandor is a beautiful place. But, much like the Feywild - and there are many portals and rifts connecting the two - it is a rugged, dangerous beauty. Under the enchanting glamors lies a world of constant danger, wild battles, and an eternal call for battle, as neither of its creator-masters believes a life without loss is worth living. An endless succession of peaceful, perfectly happy days sounds more like purgatory than paradise to those truly called for Arvandor.
Furthering this, Arvandor's creators objected to the Carceri Compact, arguing that no prison could ever be made truly escape-proof, even one forged through the powers of all gods, and that if they were to try, the presence of Carceri in the Astral Sea would poison and corrupt the Plane Above. Finally, as a compromise, they agreed to make Arvandor into a "vent" for Carceri; one-way portals from the Prison Plane allow the abominations to escape into Arvandor, which means that it is the duty of the natives to hunt them down and slay them.
The Glorious Hunt, as it's called, is fraught with danger. Simply being an Exalted does't mean you have great fighting prowess, which is why the native Exalted train ceaselessly to hone their war-skills. Furthermore, as part of its connection to Corellon and Sehahine's beliefs, deaths on the Glorious Hunt are more "serious" than normal for an Exalted. The ruesti can only perish in such a battle three to a dozen times before their existence comes to an end, passing on to whatever fate awaits a truly-dead Exalted. To say nothing of how some of the more terrible abominations have the power to flat-out destroy souls.
Ironically, despite the lengths of their lives, for many an elf or eladrin, their afterlife is incredibly short. As far as they're concerned, though, it's well-worth it; beauty and splendor balanced by the need to treat every day as if it may be their last certainly beats an eternity of tedium.
The Glorious Hunt is so well-known that not only do Exalted of Melora and Avandra often take part, but so do Exalted or epic-tier worshippers of other gods as well. Kord and Bane worshippers love to test their mettle against the monsters of Arvandor, whilst the faithful of Pelor enjoy battling the children of darkness. Even faithful of Zehir have been known to take part in the Glorious Hunt, relishing the chance to pit their poisons and murderous arts against some of the most lethal creatures in the multiverse.
Arvandor is roughly divided into two regions; the Hunting Lands, the untamed, monster-infested wilderness that makes up the majority of the Dominion's territory and where the abominations escape from Carceri, and points of civilisation, where the more conventionally pleasant aspects of life in Arvandor can happen. The former includes sites like the Dead City of Carantharas (a fallen ruesti city left to the wilderness rather than reclaimed) and the Reef Catacombs (a flooded forest of enormous petrified trees, lost since before the Dawn War), whilst the latter includes sites like the Bark Fleet (a trinity of city-sized ships woven from living trees), the Court of the Seldarine and the Empire of Estaira (a massive city of mortals who have chosen to settle in Arvandor and prove themselves worthy of life here).
The border islands of Arvandor are known as the Green Isles. Although not bedeviled by monsters to the same extent as Arvandor, life here isn't all idyllic peace. Pirates and lesser monsters abound, as do agents of dark powers. The Twisted Temples of Lyef Thierre are particularly infamous for the mad, blood-thirsty cultists who have reigned over the island for countless generations.