UPDATE 03.02.2023 - It's been brought to my attention that there is a seed that has been found that will unlock this achievement as soon as you load in. Enter the following when creating a new world:
Size - Small
Evil - Corruption
Seed - dontdigup
(Credit - sendera12)
There seems to be some confusion as to how this achievement should be unlocked and most of the other guides mention some highly inefficient methods.
Below I will outline everything you need to do to obtain this achievement within half an hour, with its counterpart only taking an additional 15 minutes.
To clarify, you only need to Corrupt / Hallow 50% of the world to unlock the respective achievements.
This guide assumes that you have already acquired the Clentaminator / Terraformer and the necessary solutions to Corrupt and Hallow your world. For those who don't, I will briefly explain how to acquire each item necessary for completing the achievement:Drill Containment Unit
- Hands down the best drill in the game, this will make digging each hellevator (A hole straight to the bottom of the world) incredibly fast.
You can craft it by combining 40 of each of the following bars at a Mythril or Orichalcum Anvil:
Luminite Bars, Chlorophyte Bars, Shroomite Bars, Spectre Bars, Hellstone Bars and Meteorite Bars.
Clentaminator - Purchased from the Steampunker for two Platinum Coins.
Terraformer - An upgraded version of the Clentaminator that is acquired by throwing the Clentaminator into the Shimmer. If possible you should aim to acquire this beforehand as it is much more efficient than the Clentaminator.
Purple Solution - Used to spread the Corruption, it can be acquired from the Steampunker for 22.5 Silver Coins per bottle whenever there is a Blood Moon or Solar Eclipse in a Corrupted world.
Blue Solution - Used to spread the Hallow, it can be acquired from the Steampunker for 22.5 Silver Coins per bottle when speaking to the Steampunker in the Hallow.
Soaring Insignia - An incredibly useful item that enables infinite flight and will allow you to quickly return to the surface after drilling a hellevator. It can be acquired from Treasure Bags dropped by the Empress of Light in Expert or Master mode (The difficulty can be adjusted at will in Journey mode).
If you don't have access to the Soaring Insignia, a Magic Mirror, Cellphone, Shellphone or Recall Potions are great alternatives to quickly teleport to the surface.
Celestial Starboard - A hoverboard that allows infinite flight and the ability to hover in place. This is a great alternative to the Soaring Insignia. It can be acquired from Treasure Bags dropped by the Moon Lord in Expert or Master mode (The difficulty can be adjusted at will in Journey mode).
This is considerably easier in Journey mode as you can speed up time to allow faster passive spread. You can also enable god mode and turn off enemy spawns which allows you to ignore all forms of danger and just focus on the two achievements. Additionally, you will be able to easily duplicate the solutions purchased from the Steampunker, giving you unlimited ammo.
Now, without further ado, lets begin:
- Start off by creating a new world with the size set to small and the evil to Corruption.
- Create a hellevator and kill the Wall of Flesh
- Dig an additional seven hellevators that are spread out along the surface (using the mini-map as a reference, you shouldn't be able to see the previous hellevator on the mini-map when you start digging the next hellevator).
- Starting from one edge of the map, aim the Terraformer straight down and spray the entire surface until you reach the other side of the map.
- Return to the first hellevator and drop down it, spraying one side as you go. On the way back up the hellevator you should spray the other side.
- Repeat the previous step for the other seven hellevators.
- Save and Exit
- Once you reload the world the achievement should unlock (if it doesn't, dig another hellevator and spray both sides before saving and exiting again. Repeat until the achievement unlocks).
With the first achievement done, you can now work on its counterpart which will go by much quicker as all of the hellevators have already been dug.
I will just clarify some incorrect information I have seen in other guides here:
Firstly, you don't need to speak to the Dryad to trigger the achievement or even have her in your world at all.
Secondly, there is no reason to place any additional blocks as only the worlds existing blocks count against you. The game doesn't take into account any blocks that cannot be corrupted or hallowed (such as ores, wood and snow).
Thirdly, the game won't update your progress until you save and exit, this is likely a glitch. As a result, you should make sure to do this after the surface and eight hellevators have been sprayed. As mentioned above, if the achievement doesn't pop, just dig another hellevator and try again.
Fourth, similarly to the above, the Dryads percentage doesn't seem to update until you save and exit... So don't rely on her to monitor progress if she is in your world.
Fifth, you CAN earn the Corruptible achievement in a Crimson world, but you won't be able to purchase the Purple Solution in the same world as it must be purchased in a world that started off with Corruption.
Sixth, this achievement can, to my knowledge, only be unlocked by the host. As such, there is no way to quickly boost this achievement as each player must create a world with 50% Corruption / Hallow themselves.
Seventh, when digging the hellevators you should start by digging a hole going straight down, the second hole however should be dug going straight up. This will save time returning to the surface and is also much quicker as any liquids (Honey, water and lava) will simply drop by you and barely slow you down. Alternating digging the holes from the surface and underworld will significantly speed up your progress.
It is worth noting that some liquids, such as water and lava, may end up combining into obsidian as they fall at different speeds. If this happens you will need to destroy these blocks on your way down later on, but it is only a minor inconvenience considering the time saved from digging a hole straight up.
Lastly, if you've made it this far, thank you for reading. I'd also be more than happy to provide the mentioned items to you so you can get started straight away. A Journey character is required.