Acid is a type of block that affects the gameplay of players. Touching it will cause a player's health to drain, similarly to lava's damaging effect.
This liquid can be spawned by bosses such as Thallasion and the Shadow Hydrakken and can be found in specific Lairs/Dungeons in the Forbidden Spires Biome. Currently not obtainable and cannot be used in Fishing, however players can still use Acid in Dungeon Creation.