The Lunar Raiding Festival

The Lunar Raiding Festival is a yearly tradition for Wood Elves where thievery is not only allowed, but encouraged, as Wood Elves compete to steal the most from neighboring lands.

The Full Day Moon

On the 26th day of the Month of Festivals, the moon is in the sky the entire day. Selene, the jealous Goddess of the Elves and the moon, was jealous that she was never allowed to see the day from the Moon. To rectify this, she adjusted the path of the moon so that once a year it would stay up in the sky in Elven territory for an entire day.
The Elves took this as an opportunity to celebrate their beloved Goddess for an entire day. Dark Elves will leave their cave for the day and gaze at the Moon, sometimes having a barbeque. High Elves will go to the Castle of the King and take turns observing from a telescope. It often devolves into fights as they argue who should see the Moon first.

Wood Elves, however, have the Lunar Raiding Festival. To honor Selene, they leave the Elven Forest for the day and go to other cities or villages. Standard targets include Dwarven lands, Draconian villages, the Draconian city of Zephys, the Human villages and cities, and even the High Elven city of Camor.

Grand Larceny

Wood Elves begin the morning in a centralized location, the Temple of Selene towards the center of the forest. This is to prevent any unfair advantages, as everyone starts together. They steal anything they can throughout the day and then reconvene back at the Temple when the moon finally goes down and the sun comes up the next day.
After reconvening, they count how much each of them stole. Specific items have different point values. Some of these point values are as follows:

Enchanted Items	400 Points
Living People	350 Points
Gold/Jewelry	300 Points
Personal Belongings	200 Points
Misc.	100 Points

These items are sometimes kept by those that steal them, and for others they return them by the next day. With

Olmand Shinebright by Jarhed

the people they take, they are always allowed to go back, but are sometimes offered a place to live among the Wood Elves. This particular thing was what brought the Human Chief of Ealla, Sirlini Glirdog, to meet her future husband Olmand Shinebright.

Obstacles

Of course, the surrounding territories do not just allow the Elves to steal from them. The Gnomish villages do, leaving out treats and other items they think the Elves may want. The Gnomes care little for their personal belongings, as most of what they have is something they can make again. They also have a special love for festivals, so they love this day.
When it comes to Draconian villages, it depends on the village and Chief. Some may wish to fight back, some may wish to steal the belongings back, and some instead wish to see how things happen. These are often some of the more challenging places to steal from, as the Elves never know what to expect.
Dwarves consider this a nice time to begin a small war in the form of a border conflict. Every year on the 26th day of the Month of Festivals, the Dwarven army just happens to be running military drills on the Elven border. It has even turned into its own holiday, known as Squadrill, where the Squads compete in various competitions (one of which may include who can stop/kill the most Elves).
Goblins are often exempt from the festival. Going into their caves would be troublesome anyway, but compounding onto that, they found the holiday fun. Instead of stealing from nearby peoples, they steal from each other on this day, so in a way the Goblins celebrate the festival as well.
Humans evacuate their villages during the week leading up to this festival so their belongings cannot be stolen. Yet the Wood Elves find that some of them will always leave things behind (either because they could not carry them or they forgot). This always makes Human territories a worthy place to steal from. This is without mentioning that, aside from Dwarves and fellow Elves, the Humans are the ones most likely to have decadent things to steal.

Selene by Jarhed

Selene

The Jealous Goddess of the Elves, Selene's main domain is that of the Moon. The Moon also serves as her Heavenly Realm, with the interior of it being another plane of existence entirely that watches over Totania directly.
Selene is known for stealing things from other Gods. When the first ocean was created on the southern side of Totania, Selene grew jealous of it and stole the concept, creating a new ocean in the North and drowning a continent that was once there. The most notable concept she stole, however, was that of a celestial body that orbited Totania. Izanagi created the Sun as his domain, and in response, Selene stole the idea of the Moon.
For this, the idea of thievery is often associated with Selene, as well as the Moon itself. So a festival in relation to both Selene and the Moon had to be about theft.

Further Celebrations

Some Wood Elves give up on the theft early in the day, and others either find it immoral or too much work. For them, they instead gather in the Temple of Selene for a unique festival that intersects with the Lunar Raids. They hunt animals or gather fruits and vegetables from around them (many are grown around the Temple for this celebration), and cook them into moon-themed treats like Moon Bread and Crescent Cake.
Often the food will be there in time for the other Wood Elves to return, allowing for the two celebrations to intertwine into one Lunar Raiding Festival.

Wood Elven Treats

Moon Bread is bread baked together in a circular shape with two different types of wheat. With this, it creates crater shapes in the bread which give it its name. Crescent Cake is a cake baked in the shape of the crescent moon, the symbol of Selene.

The largest targets of all, however, are the other Elves. High Elves have all gathered together, so stealing from their city of Camor is quite easy and always worth it, as they can take loads of gold, enchanted items, and even stragglers who are likely very weak and easy to carry. Dark Elves have left their caves to watch the moon, so taking from their caves is also an easy task. That being said, anything stolen from Dark Elves is normally returned the next day for fear of what would happen otherwise.

The Chosen Thief

After point values are totaled up, a winner is chosen among the Wood Elves. This winner is given the title of Selene's Chosen Thief and bestowed with a blessing from the Goddess for the remaining year. This blessing is carried out by the Head Priest, and what it does is grants the Chosen Thief brief invisibility once a week. This is highly sought after, as it proves useful in the hunting that is foundational to Wood Elven society.
Smaller groups sometimes also decide a winner themselves, agreeing to be a "hunting party" before the festival begins. After it ends, they gather and compare scores. The winner is then given a specific reward depending on what the party agreed to, most often given the title of Head of the Pack and allowed to lead that party in hunting for the rest of the year.