Acid (also known as corrosion) is one of the six elements in Horizon Forbidden West.

Gameplay

Both Aloy and machines are able to use acid. Acid damage can be dealt using Acid Arrows from the Hunter or Warrior Bow, Acid Shredders from Shredder Gauntlet, Acid Bombs from the Blastsling, and Acid Canister Harpoons from the Ropecaster. Additionally, the Acidspitter, Acid Bomb Launcher, and Acid Traps also inflict Acid damage. Applying Acid to an enemy's status limit produces the Corroding effect, which deals damage over time to its health and armour plating. If applied long enough, armour will start to break off. While this is in effect, armour will be significantly weakened and can break off with just one arrow.

Acid is also found as an environmental obstacle, such as exploring the ruins of the Far Zenith Launch Facility. Taking Acid damage or stepping in pools of Acid builds up the Corroded state. Once in it, Aloy will take 100 damage over 30 seconds and all outfit resistances are reduced by 40%.

Machines

Slitherfangs will spit ranged Acid at Aloy using a metalbite sac.

Acid Bristlebacks will unearth scrap and augment it with Acid for use in ranged and melee attacks.

Strategy

While using acid may be bad against lightweight machines, it can be great against apex, heavyweight machines as their armour is hard to break. This can also work on medium machines like a Ravager. The best way to use this is to fully infect the machine, then use explosive weapons such as the spike thrower or blast sling to do some real damage. No machine can live without any of its components, so once you have removed them all, it should die. Should you have no bombs, you can continually infect it until it basically falls apart.

Trivia

• Acid uses the exact icon of Corruption from Horizon Zero Dawn.