You can download Altered Damage on CurseForge and Modrinth:
  CurseForge:   https://curseforge.com/minecraft/mc-mods/altered-damage
  Modrinth:      https://modrinth.com/mod/altered-damage
To keep a better overview of all mods, the issue tracker is located in a separate repository.
  For issues, ideas, suggestions or anything else, please follow this link:
    -> Issue Tracker
Because of the way mod loader files are bundled into one jar, some extra information is needed to do a PR.
  A wiki page entry about it is available here:
    -> Pull Request Information
Requires the library mod Collective.
   This mod is part of Serilum's Customization Bundle mod.
Altered Damage is a minimalistic configurable mod that alters damage taken with a modifier by players and other entities. It's both possible to decrease and increase the damage. There is an extra config option which prevents taking fatal damage from the extra modifier, from sources such as poison and starvation.
Configurable: ( how do I configure? )
preventFatalModifiedDamage (default = true): When enabled, does not change the damage output if it would be fatal with the modifier and not fatal without. Prevents dying from for example poison and starvation.
alterEntityDamageTaken (default = true): Modifies the damage another entity receives
alterPlayerDamageTaken (default = true): Modifies the damage a player receives
entityDamageModifier (default = 2.0, min 0.01, max 20.0): The global damage modifier for other entities.
playerDamageModifier (default = 2.0, min 0.01, max 20.0): The global damage modifier for players.
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You may freely use this mod in any modpack, as long as the download remains hosted within the CurseForge or Modrinth ecosystem.
Serilum.com contains an overview and more information on all mods available.
Comments are disabled as I'm unable to keep track of all the separate pages on each mod.
For issues, ideas, suggestions or anything else there is the Github repo. Thanks!