Starting from the 1.0.0 major update. Users are able to create their own multi-mutators (these will henceforth be referred to as user-generated multi-mutator).

To create a user-generated multi-mutator, you first have to launch R.E.P.O. with the Mutators mod active. You will be able to find the following folders in your modpack profile: BepInEx\config\Mutators\MultiMutators. In the MultiMutators folder, create a .json file. You are free to choose its name.

Inside of this file is where you will define a user-generated multi-mutator. It is advised to start from an example such as the following:

{
  "Name": "Demon Ducks",
  "Description": "Ducks go crazy",
  "Weight": 0,
  "Mutators": {
    "xepos.repo-mutators:there-can-only-be-one": {},
    "xepos.repo-mutators:duck-this": {
      "aggro-cooldown": 1.0
    },
    "xepos.repo-mutators:out-with-a-bang": {
      "tier-1-enemy-explosion-radius": 3,
      "tier-1-enemy-explosion-damage": 200
    }
  }
}

The above multi-mutator consists of 3 mutators. Each one of the mutators has the option to override several of that mutator's settings. In this case, the aggro cooldown of the Apex Predator has been reduced to one second for Duck This, while the explosion radius and damage for tier one enemies has been set to 3 and 200 respectively for Out With A Bang!

There Can Only Be One is followed by empty brackets ({}), this effectively indicates that no overrides should be used and that the mutator should use the settings that are configured on the mutator itself. Each setting that is not overwritten in the multi-mutator file will use its normal configured value instead.

Mutator Definitions

As seen in the example, the mutators under the "Mutators" section do not use their raw display names. They use a namespaced name instead. For Mutators' built in Mutators, this namespaced name always consists of the prefix xepos.repo-mutators: followed by the mutator's display name in all lowercase with spaces replaced by hyphens (`-´) and and any other special characters removed (e.g. the "!" in "Out With A Bang" is removed).