The Feywild

The Feywild is a parallel plane to the Material Plane. Unlike the Material Plane, the Feywild is fueled by wild, magical energy drawn from the emotions of its inhabitants. Because of its connection to the Material Plane, the Feywild has similar topography and geography to the mortal world, though exact locations are constantly shifting and are therefore impossible to plot.
Although the general geography of the Feywild and the Material Plane is similar, the Feywild has a much more primal landscape. Nature rules in the lands of fey. Where you would find sprawling cities in the Material Plane, you might discover only hunting outposts or desolate ruins in the Plane of Faeries. Similarly, locations with patches of wilderness in the mortal realm could be vast, impassable forests in the Feywild.
This raw, primal magic makes the Feywild an extremely dangerous place, even for those who call it home. Adventurers, or those unlucky enough to unwittingly stumble into this land from the Material Plane, must ensure they are not lulled into a sense of complacency by the Feywild’s beauty. The sporadic, magical nature of this land can kill mortals as quickly as any of its dangerous inhabitants.
Due to Feywild’s close relationship with the Material Plane, crossing between the two is considered so easy that it is sometimes done by accident.
Even if visitors from the Material Plane manage to survive the untamed wilderness, innumerable deadly creatures call the Plane of Faeries home. Because the magic that shapes the Feywild is more chaotic and powerful than the Material Plane, even its most common creatures can be infused with power that can rival hardened adventurers.
Thus, those who journey to the Feywild — whether on purpose or by chance — must tread carefully, for even the most innocuous-looking clearing or creature could lead to their end.
Very few know what it is actually like and what it looks like, mostly due to the number of people that never make it back.
Feywild Magic:

• Tales speak of children kidnapped by fey creatures and spirited away to the Feywild, only to return to their parents years later without having aged a day, and with no memories of their captors or the realm they came from. Likewise, adventurers who return from an excursion to the Feywild are often alarmed to discover upon their return that time flows differently on the Plane of Faerie, and that the memories of their visit are hazy. You can use these optional rules to reflect the strange magic that suffuses the plane.
• Memory Loss: A creature that leaves the Feywild must make a DC 10 Wisdom saving throw. Fey creatures automatically succeed on the saving throw, as do any creatures, like elves, that have the Fey Ancestry trait. A creature that fails the saving throw remembers nothing from its time spent in the Feywild. On a successful save, the creature’s memories remain intact but are a little hazy. Any spell that can end a curse can restore the creature’s lost memories.
• Time Warp: While time seems to pass normally in the Feywild, characters might spend a day there and realize, upon leaving the plane, that less or more time has elapsed everywhere else in the multiverse. Whenever a creature or group of creatures leaves the Feywild after spending at least 1 day on that plane, you can choose a time change that works best for your campaign, if any, or roll on the Feywild Time Warp table. A wish spell can be used to remove the effect on up to ten creatures. Some powerful fey have the ability to grant such wishes and might do so if the beneficiaries agree to subject themselves to a geas spell and complete a quest after the wish spell is cast.

Fey Crossings:

• They can be found in ruins and old forests, often changing locations based on the weather, alignment of the planets, or time of year. A traveler can also pass through a fey crossing by entering a clearing, wading into a pool, stepping into a circle of mushrooms, or crawling under the trunk of a tree. To the traveler, it seems like he or she has simply walked into the Feywild with a step. To an observer, the traveler is there one moment and gone the next. These portals are random enough that unwitting travelers can stumble across the barrier between the realms by being in the wrong place at the wrong time. By the time the hapless traveler realizes that something is amiss, the portal might disappear, not to return for an hour, a day, or a century.
• While the random convergences of the planes are dangerous and chaotic, there are areas that act as permanent fey crossings for the purpose of intentional travel between the Material Plane and the Feywild. These crossings are usually well-guarded secrets, as the fey don’t want just anybody to be given carte blanche access to the powerful magics that reside in the land of faeries.
• If someone looking for access to the Feywild, they may seek out assistance. For instance, they could navigate a treacherous swamp and bargain with a hag for the knowledge, or protect a patch of wilderness against an industrious noble for a druid who knows the fey’s secrets.
• Whether travelers arrive intentionally or by accident, the chaotic Plane of Faeries does not show favor or mercy. The Feywild is deadly, there are no two ways around it. Because the Feywild has few civilized areas and the roads between them are unpredictable, traveling from one part of the Feywild to another is dangerous. Adventurers looking to move between cities in the Feywild might have to cross through swamps full of poisonous gas or forests that attempt to trap travelers in a never-ending maze.