You can tell a Blood Moon is out when the sky turns red. There is something about it that causes monsters to swarm.
A Blood Moon is a common randomly occurring event that takes place over the course of an entire night, from 7:30 PM to 4:30 AM; however, a Blood Moon can also be initiated when the player uses a Bloody Tear. It causes several hazards for its duration: Enemy spawns increase, even near the player's Home and NPCs (where enemies do not normally spawn), Zombies become able to open Doors, and Bunnies, Penguins, and Goldfish transform into dangerous enemies, along with other effects (see below). Blood Moons are signaled by the message "The Blood Moon is rising..." in the lower left corner of the screen (or the top middle of the screen on Mobile). The moon, sky, water, and rain will appear red for the duration of the event. A reddish-pink filter will also be present in all above-ground areas. Blood Moons disable the ability to speed up time whilst sleeping in a bed.
A Blood Moon will only occur if at least one player in the world has more than 120 life, and only on nights when a moon is present (any night except a new moon). Given those criteria, a Blood Moon has a
11.11*1/9 (11.11%) chance of occurring.
- The spawn rate of enemies on the surface increases. Dripplers, Blood Zombies, The Groom, The Bride, and the Clown (if in Hardmode) have a chance to spawn. Enemies not only spawn faster, but more are spawned than can normally exist on-screen at once. This works no matter the environment, so Corruption and Crimson enemies can also swarm even more than they normally would, for example.
- Enemies can even spawn near NPCs and their houses, whereas those usually suppress enemy spawns. Player-placed walls are not necessarily safe during this event.
- Zombies and their counterparts can open Doors.
- Goldfish become Corrupt Goldfish/Vicious Goldfish, Bunnies become Corrupt Bunnies/Vicious Bunnies, and Penguins become Corrupt Penguins/Vicious Penguins. Those spawned from Statues are Corrupt or Vicious , and they do not revert to regular Goldfish or Bunnies after the Blood Moon is over. If it is raining during the event, transformed Goldfish will flop around on the ground, rather than walk.
- The Merchant sells Throwing Knives.
- The Arms Dealer sells Silver Bullets (in Desktop version, Console version, Mobile version, and Nintendo Switch version, only if silver is present in the world), and Tungsten Bullets if tungsten is present (Pre-Hardmode. In Hardmode, the Arms Dealer will always sell Silver or Tungsten Bullets ).
- The Clothier sells the Mime Mask, Fallen Tuxedo Shirt and Fallen Tuxedo Pants.
- The Dryad stops selling Purification Powder, Sunflowers, and Grass Seeds.
- If the world was created with the Corruption (or she is in a Graveyard in Hardmode), she will sell Vile Powder and Corrupt Seeds.
- If the world was created with the Crimson (or she is in a Graveyard in Hardmode), she will sell Vicious Powder and Crimson Seeds.
- On the Old-gen console version and Nintendo version, she will also sell Sparkly Wings during Hardmode.
- The Painter sells the Evil Presence painting.
- The Dye Trader sells Bloodbath Dye.
- The Steampunker sells Purple Solution if the Corruption is present, or Red Solution if the Crimson is present instead of Green Solution.
- The Cyborg sells Rocket II ammunition.
- The Skeleton Merchant sells the Slap Hand during Hardmode.
- Deathweed blooms. Blood moons (and Full Moons on Desktop, Console, Mobile, Switch, and tModLoader) are the only times you can harvest Deathweed Seeds from Deathweed (with the exception of harvesting with a Staff of Regrowth).
- Most NPCs have their own unique lines commenting on the event.
- The Zoologist NPC will transform into her werefox form regardless of the moon phase.
- Fishing power is 1.1x stronger, and can provide some unique items and spawn unique enemies, including the Dreadnautilus.
- Visual effects:
- Almost all water will turn red, including Rain. Exception: The Ocean will not turn completely red, though it will be affected by the screen filter.
- A red filter will be applied to the screen as well, shifting the colors of all entities and light towards red and purple shades.
- This will also affect the projectile colors of many weapons.
- Placed Living Cursed Fire Blocks turn yellow, making a unique effect.
- The Glowing Mushroom Biome, which is normally blue, will have the red shader make it appear pink-purple.
- The Blood Moon's effects on enemy spawn rates stack with that of the Water Candle and Battle Potion.
- A Blood Moon only affects spawn rates above the surface. Spawn rates below the surface remain the same.
- Whether or not a Blood Moon will occur is determined at dusk each night.
- Every nightfall has an equal chance of being a Blood Moon and does not change if the previous night was a Blood Moon. It is possible to have four or more Blood Moons in a row and, conversely, a Blood Moon will not necessarily occur even over the course of many in-game weeks.
- In a multiplayer game, using the time adjustment server commands (dawn, noon, dusk, midnight) will not trigger the Blood Moon check, and so using "dusk" repeatedly does not force a Blood Moon to occur.
- Water in an Ocean biome will not turn red even though all other water in biomes will. However, the blue water is still affected by the red shader, giving it a purple color.
- If a player chooses to, they can cancel a Blood Moon by summoning the Pumpkin Moon or Frost Moon.
- A Blood Moon can happen in the middle of a Pirate Invasion. The invasion will still go on until it ends, then the Blood Moon starts. A Blood Moon can also occur during Slime Rain.
- Blood Moons occur more often than Solar Eclipses, as Solar Eclipses have a
5*1/20 (5%) chance to happen each day (when the criteria are met).
- If a Blood Moon and Full Moon coincide, Werewolves will spawn with increased frequency, rather than Zombies, but the special Zombies will still spawn.
- Similar to the Solar Eclipse, a Blood Moon will increase the spawn rate of Truffle Worms once in Hardmode.
- The player cannot speed up a Blood Moon by sleeping.
- At daybreak, all unkilled special enemies will attempt to flee the screen.
- During a Blood Moon in Hardmode, every enemy and NPC has a
0.1*1/1000 (0.1%) chance of dropping the KO Cannon. This means that even though it is rare, like with the Blessed Apple, the large number of drop chances makes this easier to farm, and the KO Cannon is likely to aid a player in early Hardmode.
- Simply placing a block in front of a door will prevent Zombies from being able to open the door.
- If the player sees the notification that a Blood Moon is rising and they are under-equipped to defeat it, they should get underground as quickly as possible. Going indoors will not save them, nor will standing around outside. The Blood Moon gives enemies dangerous abilities, such as the ability to open doors.
- Although the Blood Moon is typically treated as a deadly event, it is possible to enjoy the event. Once the player has max health and good weapons and armor, the new enemies are not a serious threat, especially if they have prepared their base. As the Tavernkeep says, "You know, where I'm from, a Blood Moon is actually just an excuse to get some fresh air."
- The Blood Moon is a great place to use weapons with the Cursed Inferno debuff. It does significantly increased damage since 1.4.1, and most Blood Moon enemies are fast, meaning you'll be dodging a lot more than in regular gameplay, and making Cursed Inferno (with its damage over time) much more useful.
- In real life, the Moon appears red during a lunar eclipse, which is sometimes referred to as a "Blood Moon". As sunlight passes into the shadow through the atmosphere, the Moon is given a red/orange color due to the amount of air the light passes through. This is the same phenomenon that gives sunsets and sunrises such colors.
- When a real Blood Moon occurred on April 14, 2014, a warning was jokingly announced on the official Terraria forums.
- The Blood Moon and Underworld share the same track on the Nintendo version. Verify
- During a Blood Moon, all female NPCs except the Party Girl and the Princess use more irritable or aggressive dialogue than normal. This is a reference to the fact that some women in real life become irritable or aggressive due to premenstrual syndrome. Both the menstrual cycle and the real-world Moon cycle occur approximately every 28 days.
- Female player characters are not subject to such changes - all dialogue between the player and NPCs is as normal for blood moons and the player is not implied through the NPCs to appear more irritable.
- The Blood Moon is the only thing in the game with it's song title (Eerie) not being named after what it plays for. (e.g. The song that plays at nighttime in the Forest biome is named "Overworld (Night)")
- Desktop 18.104.22.168:
- Blood moon now increases fishing power.
- Added the Chum Bucket, an item that increases fishing power.
- Added 5 new enemies, the Blood Eel, Zombie Merman, Wandering Eye Fish, Hemogoblin Shark and Dreadnautilus.
- Enemies drop extra money during Blood Moons.
- Can now be summoned using the Bloody Tear summoning item.
- Desktop 22.214.171.124:
- The Bride, Blood Zombie and Drippler introduced, including their drops and banners.
- Improved atmosphere.
- The Skeleton Merchant was introduced, and sells the Slap Hand during the night of a Blood Moon.
- The Clothier sells the Fallen Tuxedo Shirt and Fallen Tuxedo Pants during the night of a Blood Moon.
- Desktop 1.2:
- Desktop 1.1: The chance of a Blood Moon was decreased to 1/9 from its previous chance of 1/7.
- Desktop-Release: Introduced.
- Console-Release: Introduced.
- Switch 1.0.711.6: Introduced.
- Mobile-Release: Introduced.
- 3DS-Release: Introduced.
- Information taken from the Desktop 126.96.36.199 source code, method
Terraria.NPC.cs. There may be inaccuracies, as the current Desktop version is 188.8.131.52.
- www.terrariaonline.com → Forums → News → Dev Blog → thread: The Blood Moon is Rising...