Holy Water

Each of the three bottles converts a small circle of ground where it lands. Holy Water plants Hallow, Unholy Water plants Corruption, Blood Water plants Crimson. Anything caught inside the circle takes a little damage on the way through, but that damage belongs to no class at all, so no accessory, buff or armor bonus will ever raise it. Treat these as terraforming tools that happen to sting, not as weapons.

Spot work. Seeding a small pocket of Hallow underground to start pulling in the enemies and materials that only appear there, flipping the ground around a fishing hole to change what bites, or nudging a biome line a few tiles so a house counts as the right biome. Anything larger than that wants the Clentaminator or its upgrade the Terraformer, which paints from a long way off instead of asking you to walk to every tile you want changed.

The two evil bottles can be made before Hardmode. The sand they need comes from converting ordinary sand with Vile or Vicious Powder, so nothing really gates them. Holy Water is the odd one out, since its ingredients only exist after the Wall of Flesh and there is no early workaround. If you want to spread a biome on a fresh world, it will be one of the evil ones.

Thrown powders reverse the process, so nothing here is permanent. Purification Powder is the usual cleanup after a bottle lands somewhere you did not want it. Newer versions also let the bottles recolor torches they touch, which sounds trivial until a stray throw redecorates a corridor you had lit deliberately.