Blood Moon Horde

The Blood Moon Horde is a major recurring event in 7 Days to Die. During this event, a large number of zombies will aggressively seek out the player, making it one of the most challenging and crucial aspects of survival in the game.

Overview

A Blood Moon Horde consists of an early-morning indicator, late-afternoon warnings, an initial attack followed by subsequent waves of attack, and the conclusion of the event the following morning. The zombies spawned during a Blood Moon Horde know exactly where all players are regardless of how quiet the players are, how many walls they hide behind, or how deep underground they go. Zombies will break down obstacles, climb, or dig as they are able in order to reach the player.

When It Happens

• Frequency: Every 7th day (e.g., Day 7, Day 14, Day 21, etc.)
• Time: The horde starts at 22:00 and ends at 04:00 the next day.

Blood Moon Horde settings can be changed in the Game Settings, including the frequency, predictability, and challenge of the event.

Indicator and Warnings

At 08:00 on the day of a Blood Moon, the day number in the HUD will turn red. This is your first indication that the horde will be coming that night. At 18:00 you will hear a crack of thunder, and the sky will slowly start to turn red. By 21:00 the sky will be very red, and the storm will be in full swing. You are definitely running out of time!

Initial Attack Wave

At 22:00, there will be a directionless scream announcing the beginning of the horde. Shortly thereafter, the initial wave of zombies will spawn some distance away the player and immediately begin running towards them. The exact number of zombies in this initial wave is determined by the Game Stage and the number of players in close proximity. There is a limit to the number of zombies per player that will exist at one time. As zombies are killed, replacement zombies will spawn a distance away and join the attack, until all zombies in this initial wave are killed. The initial attack wave also has a maximum duration. When all zombies in the initial attack wave are killed or the maximum duration is reached, the attack wave will be considered completed.

Subsequent Waves

Once the initial attack wave has completed, subsequent attack waves will begin. Each subsequent wave is more numerous and more difficult. The total number of waves to be dealt with is determined by the Game Stage.

As in the initial attack wave, zombies that are killed will continue to be replaced until all the zombies in that wave are killed or the maximum duration is reached.

Conclusion at 04:00

At 04:00, the Blood Moon Horde will end. The sky will turn from red to clear, and any remaining Blood Moon Horde zombies will return to normal behavior.

Rewards

Surviving a Blood Moon Horde can yield significant rewards:

• Experience Points: Killing zombies during the horde can result in substantial XP gains.
• Loot: Zombies killed during the horde can drop valuable loot.

Trivia

• The Blood Moon effect causes the sky to turn a distinct red color, creating a foreboding atmosphere.
• The first Blood Moon Horde is often considered a rite of passage for new players.

Blood Moon Game Mechanics

If you are interested in more details of the mechanics behind Blood Moon Hordes, continue reading.

Blood Moon Frequency

On default Game Settings, the Blood Moon will occur predictably every 7 days. Both single-player and dedicated server games can modify this (or disable it entirely). The two related settings are:

SP Setting	Dedicated Server	Default	Usage
Blood Moon Frequency	BloodMoonFrequency	7	The 'base' frequency of the Blood Moon; Blood Moons can be disabled with this setting
Blood Moon Range	BloodMoonRange	0	The number of days, in addition to the 'base', that the Blood Moon can shift later than normal.

Note that each Blood Moon Frequency setting is relative to the previous Blood Moon. The next blood moon occurs on frequency + the range.

Example 1: Setting frequency to 7 and range to 1 means that the first Blood Moon might occur on day 7 or 8. If the Blood Moon is on Day 8, then the next Blood Moon might occur on (8 + 7 + up to 1 day), meaning days 15 or 16.
Example 2: Setting Frequency to 10 and range to 3 means that the first Blood Moon could be on days 10-13. If the 1st occurs on day 12, then the 2nd will occur on (12 + 10 + up to 3 days), meaning days 22-25.
Example 3: Setting Frequency to 1 will cause a Blood Moon every night, if you're into that sort of thing.

Horde Spawning Mechanics

Simplified

The simplified version of the mechanics are this:

1. Number and strength of waves is determined by your Game Stage.
2. The number of actual zombies you will fight at any one time is determined by Game Stage, number of players, and Game Settings.
3. Each wave has a total number of zombies and a timer - either killing an entire wave or running out of time will start the next wave. Any remaining unspawned zombies in the expired wave will not spawn.
4. Each wave is finite; if you can kill all of the zombies in the final wave there will be no 'trickle' of zombies the remainder of the night.
5. At 04:00, the event is completed, and all remaining Blood Moon-spawned zombies will revert to normal behavior.

The Full Details

The File Where it Happens: Gamestages.xml

The configuration file which controls Blood Moon Horde spawning is gamestages.xml. Here is an example for Game Stage 59 which we will walk through. Each <spawn ... /> line identifies a single wave of the overall horde.

<gamestage stage="59">
  <spawn group="feralHordeStageGS49" num="84" maxAlive="20" duration="2" interval="29"/>
  <spawn group="feralHordeStageGS54" num="84" maxAlive="20" duration="2" interval="18"/>
  <spawn group="feralHordeStageGS59" num="84" maxAlive="20" duration="7"/>
</gamestage>

Here is how to interpret the parameters in that block.

Parameter	Meaning
stage="59"	Your Game Stage must be at least 59 for this rule to take effect; the next rule is for GS 64, so this GS 59 rule will apply for GS 59-63.
group="feralHordeStageGS49"	This identifies the horde group (list of zombies) which will be pulled from for this wave (found in entitygroups.xml)
num="84"	This is the 'bucket size' for the wave - the total number of zombies that can spawn during the wave (not all at once though)
maxAlive="20"	This is the per-player maximum number of zombies that will spawn at once; note that you might not actually see this many due to other restrictions (see below)
duration="2"	This is the maximum duration of the wave in in-game hours; if you kill the whole wave before 2 hours, the next wave will start after the 'interval'
interval="29"	This is the time between waves in real-world seconds; if you kill a wave or its timer runs out you will have a breather for this many seconds before the next wave

How Many Zombies Could There Be?

The total possible number of zombies which can spawn during a Blood Moon Horde can be found by adding up the 'num' parameter for all waves in the appropriate <gamestage> entry in gamestages.xml. In the example shown above, the total number of possible zombies is 84 + 84 + 84 = 252. The actual number of zombies spawned at the same time will likely be different and the total number of zombies actually fought might be different depending on how efficient you are at killing them.

How Many Zombies Will Spawn At Once?

The total number of zombies which will spawn at once - say, in the initial attack on your base - is the lesser of the following three values.

Value	Meaning	Default	Where To Change It
Max Spawned Zombies	The game-wide maximum number of zombies that can be spawned in the world (natural or horde)	64	console command 'sg MaxSpawnedZombies XX' (SP) serverconfig.xml 'MaxSpawnedZombies' (Dedicated)
Blood Moon Enemy Count X # of Players	The per-player maximum number of zombies to spawn on Blood Moon (independent of Game Stage or anything else)	8	Advanced Game Settings (SP) serverconfig.xml 'BloodMoonEnemyCount' (Dedicated)
maxAlive for Horde Wave X # of Players	The per-player maximum number of zombies to spawn for a given Game Stage & horde wave	<depends on GS and wave>	gamestages.xml (not recommended)

Example 1:

• Single-player game
• Max Spawned Zombies = 64 (default)
• Blood Moon Enemy Count = 8 (default)
• Parameter 'maxAlive' for the horde wave = 22
• Parameter 'num' for the horde wave = 100

In this example, the limiting factor is Blood Moon Enemy Count, so only 8 zombies will spawn from the horde at once. As they are killed, new horde zombies will spawn to keep the total at 8.

Example 2:

• Single-player game
• Max Spawned Zombies = 64 (default)
• Blood Moon Enemy Count = 32
• Parameter 'maxAlive' for the horde wave = 22
• Parameter 'num' for the horde wave = 100

In this example, now the limiting factor is the 'maxAlive' parameter for the horde wave, which is 22. As Game Stage increases, eventually maxAlive will grow to be greater than the Blood Moon Enemy Count setting (32) and then the limit would be 32 at once.

Example 3:

• Multiplayer dedicated server game with 3 players
• Max Spawned Zombies = 64 (default)
• Blood Moon Enemy Count = 32
• Parameter 'maxAlive' for the horde wave = 22
• Parameter 'num' for the horde wave = 100

In this example, the limiting factor is Max Spawned Zombies. This is because 'maxAlive' (22) times the number of players (3) equals 66 total spawns. However the Max Spawned Zombies setting is 64, so only 64 spawns would happen at once.

Max Spawned Zombies Setting and Natural Spawns

At the beginning of a Blood Moon Horde there may be some natural spawns in the area. These spawns do count against the Max Spawned Zombies limit, and the Blood Moon horde will only spawn zombies until the max is hit, even if this is less than would otherwise be allowed. So in Example 3 above, if there were 10 naturally-spawned zombies milling around when the horde started, the horde would only be able to spawn in 54 zombies (64 max minus the 10 already in the world) to start with. Eventually the natural spawns will time out (or be killed) and pretty much all living zombies will be from the horde spawner.

Kill 'Em All vs Horde Wave Duration

Each horde wave has a duration expressed in in-game hours. In the example above the first two waves have a duration of 2 hours and the last has a duration of 7 hours. Note that the entire Blood Moon lasts for 6 hours, so a duration of 7 essentially means 'for all the time remaining until 0400'.

When fighting or evading the horde, there are three possible results for each wave:

1. You kill all of the zombies in the wave (the 'num' parameter) - in this case the next wave will start immediately after the 'interval' parameter of the wave you killed
2. You fight/evade the wave until its duration expires - in this case the next wave will start after 'interval'; any remaining zombies still must be killed or evaded
3. You fight/evade the wave until 04:00 - in this case all remaining zombies will switch to normal behavior and you can clean them up or evade them like any other zombie

If you repeatedly achieve result #1, it is quite possible to 'beat' the Blood Moon well before 04:00. After that there will be no more spawns (see #Customizations below). If you at least achieve result #1 on the final wave, you will 'beat' Blood Moon and spawns will cease. At higher Game Stages this is increasingly difficult as the waves are more numerous and have a larger total spawn amount.

Multiplayer and Performance Considerations

The primary differences between single-player and multiplayer hordes are the per-player horde spawn limits. These are 'Blood Moon Enemy Count' and 'maxAlive' described above. Generally you will not want to mess with maxAlive unless you are building a mod, so to adjust the multiplayer experience you will want to adjust Blood Moon Enemy Count. Increasing the value will - especially as your Game Stage passes about 50 or so - make the 'horde fight' bigger in a very direct way. Double the value and you will see double the zombies attacking your base at the same time. This has significant performance impacts for both the server and the clients.

The global setting affecting single-player, multiplayer, and performance is Max Spawned Zombies. Increasing this value will allow more zombies in your world at all times as well as lifting the ultimate cap for Blood Moon hordes. This is a hard limit for the entire game so, for example, in a 4-player game setting Max Spawned Zombies to 100 while having Blood Moon Enemy Count at 30 will not make a lot of sense, since the 4 x 30 = 120 desired max for Blood Moon will be capped by the game-wide Max Spawned Zombies setting of 100.

Customizations

The following customizations are just a sample of changes you can make to adjust the Blood Moon Horde to your liking.

If You Want	Change This
No Blood Moon Horde	Game Basic Settings - Blood Moon Frequency 'disabled' (SP) BloodMoonFrequency=0 (Dedicated)
Irregularly timed Blood Moons	Game Basic Settings - Blood Moon Range (SP) BloodMoonRange (Dedicated)
Short/no Blood Moon warning	Game Basic Settings - Blood Moon Warning (SP) BloodMoonWarning=(hour of day) (Dedicated)
Faster/slower Blood Moon zombies	Game Basic Settings - Zombie Blood Moon Speed (SP) ZombieBMMove (Dedicated)
More zombies at once	Game Advanced Settings - Blood Moon Enemy Count (SP) BloodMoonEnemyCount(Dedicated) See above for details on mechanics
More zombies total during horde	Edit appropriate <stage .../> entries to increase 'num' parameter in gamestages.xml
A guaranteed non-stop final wave	Edit appropriate final <stage .../> entries (within each <gamestage> group) in gamestages.xml to change num="9999"