The Enemy Spawn Director

The Enemy Spawn Director (ESD) monitors players throughout a mission and dynamically adjusts enemy spawns, locations, and numbers based on player performance. The ESD uses a system of Stress Levels and Pressure to regulate intensity, ensuring gameplay remains challenging without overwhelming players.

For a detailed guide on spawn systems, see Spawn System Info.

Key Files Controlling the ESD

Many files contribute to enemy spawning, but the two primary files are:

esd_manager.sso
esd_factions_and_compositions_library.sso

Both files control what enemies spawn, how many spawn, and under what conditions.

esd_manager.sso

The ESD Manager controls spawns during the Wave Phase of the spawn cycle, adjusting spawn rates and enemy types based on player Stress and Pressure values.

Location: server_pc\root\paks\server\default\default_other.pak\ssl\spawn_system\enemy_spawn_director\esd_manager.sso

Wave Phase settings inside the ESD Manager

Phase Length Settings

Phases are categorized into SHORT, NORMAL, and LONG lengths based on Stress Level.
High Stress reduces Wave Phase time, while extending Breather/Tension phases.
All phase durations are measured in seconds.

Pressure Settings

Spawns only occur once the player's Pressure Score exceeds a threshold.
Example:
- Standard spawn activation threshold: 100 Pressure.

Tuning these values modifies when and how enemy spawns escalate.

Enemy Spawn Packs

Each spawn entry is called an Enemy Spawn Pack and contains:

isEnabled: (True/False) flag to toggle the spawn.
minCount, maxCount, or amount: control how many enemies spawn.
archetypeUid: defines which enemy type spawns.
combatType: (ANY, RANGED, MELEE) priority setting.
cooldown range: sets minimum/maximum time before the spawn can reoccur.

Extra Pack Variants

Spawn Packs can include additional units via extraPackVariants, creating richer, more varied encounters.

Each variant must have a unique name (use underscores, no spaces).
Defined in SubPackDescs.
Variants can specify:
- archetypeUid (enemy type)
- Spawn amount
- excludedDifficultyLevels (0 = Minimal, 5 = Absolute)

How Enemy Spawning Selection Works

Spawning is governed by Random Number Generation (RNG). Each active spawn pack is selected randomly after cooldowns expire.

Cooldown Timers

Separate cooldowns are maintained for different factions (e.g., Tyranids vs Chaos).
Cooldowns are measured in seconds.

Example:

Base cooldown: 240 seconds → New spawn selection every 4 minutes.

Difficulty Modifiers

Cooldown times are multiplied based on difficulty:
- Easy difficulties: Cooldown × 1.5
- Hard difficulties: Cooldown × 0.8 or lower

Example:

Base cooldown: 240s
Modifier (1.5×): 360s
Modifier (0.7×): 168s

esd_factions_and_compositions_library.sso

The ESD Factions and Compositions Library manages spawning during the Tension Phase.

Location: server_pc\root\paks\server\default\default_other.pak\ssl\spawn_system\enemy_spawn_director\esd_factions_and_compositions_library.sso

Tension Phase Spawn Packs

Packs define entire groups of enemies rather than single spawns.
Each Spawn Pack contains multiple SubPacks.

Naming rules:

Spawn Pack names must be unique (only underscores allowed).
SubPack names must be unique within each pack.

Example:

Spawn Pack HormagauntSergeants_idle includes:
- 20 Hormagaunts
- 5 Hormagaunt Sergeants

Behavior Settings

packType: defines behavior on spawn (AGGRO or IDLE).
combatType: prioritizes RANGED or MELEE behavior.

What Can I Spawn?

By default:

Extremis, Terminus, and Mini-Boss enemies spawn primarily during Wave Phases (esd_manager.sso).

However:

Any enemy type (Tyranid, Chaos, or others) can be spawned by specifying the appropriate archetypeUid.
Mixed spawns are possible — e.g., Rubric Marines spawning with Hormagaunts.

See Archetypes for a full list of spawnable enemies.

This page is incomplete. The Tech-Priests recording this data exhausted their memory banks. Contributions are welcome.