Events are periodical or random time periods when special mobs are spawned. There are 7 events in the mod, 4 occur at night, 3 occur during the day. Because events do not occur all the time, it is important to take advantage of an event the moment it is announced on chat.
It is possible for multiple events to occur at the same time.
In Minecraft the moon goes through a Lunar Cycle. Each Lunar Cycle consists of 8 moon phases; on the 8th moon phase, the Full Moon comes out. The first night of the game is always a Full Moon, so it is recommended that the player makes a bed as soon as possible to skip the night. However, if the player is skilled enough, it may be a good idea for the player to stay outside and fight the mobs to train the Hunter skill.
According to the Minecraft Wiki, each lunar cycle takes about 2 hours and 30 minutes. This means that assuming no nights are skipped through usage of a bed, a Full Moon Event will occur every 2 hours and 30 minutes of gameplay.
On such a night the Full Moon Event begins and special mobs can spawn. All of these mobs can be quite dangerous compared to normal night mobs. The Skellox and Scrubby are really fast and can outrun sprinting players, and the Night Watcher and Dark Beast are really tanky and use Blindness to confuse players (which can be dangerous when the faster mobs are around).
The Bloodhunt Event has a 20% chance of occurring every night. When a Bloodhunt Event occurs, the message "The Hunt for Blood has Begun" will be announced on chat.
Special mobs can spawn during the Bloodhunt event. The mobs spawned during the event has a chance to drop realmstones required to enter The Abyss.
The Anemia is a rather dangerous mob as it shoots explosive projectiles that can easily kill a player and destroy said player's items, so if the player is ill-equipped it may be a better idea to skip the Bloodhunt event.
The Soul Scurry event has a 10% chance of occurring each night. When a Soul Scurry event occurs, the message "Souls are out scurrying tonight..." will be announced on chat. When the event ends, the message "The souls disappear once again." will be announced.
During the Soul Scurry event, six ghost versions of common Overworld mobs will spawn. These mobs are translucent, ghostly versions of their in-the-flesh counterparts and usually have higher health and/or attack strength. These mobs all drop Ghostly Stones, which can be used on the Ascension Shrine to increase Augury levels, traded to the Primordial Banker for Gold Coins, or crafted with Mystite Ingots to make special Extraction tools.
The Death Day Event has a 1 in 25 (4%) chance to occur each day. When a Death Day Event occurs the message "Today is a good day to die." will be announced in the chat. When the event ends the message "The day of death has ended." will be announced.
The Death Day Event is particularly important because the Death Hunter spawns during this event. The Death Hunter is the only mob that drops the Immortallis Realmstone. The Headless Destroyer can be farmed early on for Hunter experience, but the other two mobs don't really do anything significant.
The Creep Day Event has a 1 in 20 (5%) chance to occur each day. When a Creep Day Event occurs the message "The day has become a lot creepier." will be announced in the chat. Creeper-like UFOs called Hosts will spawn in the world. When the event ends the message "The day ends, and so does the creeping." will be announced.
This event is very important, for the Hosts will drop Creeponia Realmstones. This can also be a good time to grind for gunpowder.
The Big Day Event has a 1 in 20 (5%) chance to occur each day. When a Big Day Event occurs the message "Today is a big day." will be announced in the chat. Elemental Giants will spawn in their respective biomes, and can be harvested for materials. When the event ends the message "The day disappears slowly as the sun sets." will be announced.
The Wood Giant is particularly useful as they are not only the most common but can be farmed for half a stack of Oak Wood each, which will usually last the player for quite a while.
The Lunar Event has a 1 in 15 (6.67%) chance to occur each night. When a Lunar Event occurs the message "Strange things are upon us." will be announced in the chat. When the event ends the message "The strange creatures begin to vanish." will be announced.
Lunar Event mobs all drop the Orbulon item, which can be used to craft Lunar Bricks and trade with the Lottoman for Magic Repair Dust.