You can tell a Blood Moon is out when the sky turns red. There is something about it that causes monsters to swarm.
Blood Moons are signaled by the status message "The Blood Moon is rising...". All the water in the world, even underground, will turn blood-red for the duration of the event, including rain and the moon itself. A red filter will be applied to the screen when the player is on the surface layer.
The event will bring new and dangerous enemies, while also changing their behaviour and spawning conditions (see below).
During a Blood Moon, the ability to speed up time whilst sleeping in a bed is disabled. Also, the player's Fishing Power is increased by 1.1 times. However, fishing could also bring about unique enemies.
In order for a Blood Moon to naturally occur, the following criteria must be met:
- It will only occur if at least one player in the world has more than 120 health.
- It can only occur on nights when the moon phase is not new moon.
- It will not occur if the Eye of Cthulhu will spawn on that night.
- Given those criteria, a Blood Moon has a
11.11*1/9 (11.11%) chance of occurring.
- Given those criteria, a Blood Moon has a
A Blood Moon can be initiated manually at night by using a Bloody Tear, and does not require said criteria to be met.
Whether a Blood Moon will occur naturally 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.
- The spawn rate of enemies on the surface increases. Not only do they spawn faster, but more are spawned than can normally exist on-screen at once.
- Enemies can spawn near towns, even though those normally suppress enemy spawns.
- Zombies and their counterparts become able to open Doors.
- Goldfish, Bunnies, and Penguins turn into Corrupt Goldfish/Vicious Goldfish, Corrupt Bunnies/Vicious Bunnies, and Corrupt Penguins/Vicious Penguins respectively.
- Deathweed blooms during a Blood Moon.
- Most NPCs have their own unique lines commenting on the event.
- The Zoologist NPC will always transform into her werefox form.
- A red filter will be applied to the screen, shifting the colours of all entities and light towards red and purple shades.
- Almost all water will turn red, including rain.
- The Oceans will not turn red, though it will be affected by the screen filter.
- The filter will also alter the projectile colours of many weapons.
- Placed Living Cursed Fire Blocks turn yellow, creating a unique effect.
- The Glowing Mushroom Biome, which is normally blue, will appear pink-purple because of the red shader.
- The Blood Moon's effects on enemy spawn rates stack with that of the Water Candle and Battle Potion.
- 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.
- 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.
- It 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, instead of Zombies. Other spawns won't be affected.
- Similar to the Solar Eclipse, a Blood Moon will increase the spawn rate of Truffle Worms once in Hardmode.
- 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, and there will be much more of them.
- 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 armour, 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 increase 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 colour due to the amount of air the light passes through. This is the same phenomenon that gives sunsets and sunrises their colours.
- When a real Blood Moon occurred on April 14, 2014, a warning was jokingly announced on the official Terraria forums.
- 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.
- Desktop 126.96.36.199:
- 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 188.8.131.52:
- 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 184.108.40.206 source code, method
- Information taken from the Desktop 220.127.116.11 source code, method
Terraria.NPC.cs. There may be inaccuracies, as the current Desktop version is 18.104.22.168.
- www.terrariaonline.com → Forums → News → Dev Blog → thread: The Blood Moon is Rising...