Thrown Water

Thrown Water refers to a set of three consumable weapons that each convert a small area into a biome (Hallow, Corruption or Crimson for Holy Water, Unholy Water and Blood Water respectively) when thrown. This conversion affects a roughly circular area with a radius of four blocks from the center. Enemies within this radius are also damaged slightly; this damage is flat and cannot be modified by any buffs or equipment.

Holy Water is only available in Hardmode. It is possible for Corruption or Crimson deserts to be generated naturally with the world, making the other two throwable waters available from the beginning of the game, but if they are not created at this point then these biomes will not spread onto Sand until Hardmode begins, making these items unavailable until then.

Trivia

 * The Holy Water, including its sprite and the way it's thrown, is possibly a reference to the Castlevania item of the same name