Game Mechanics Corruption/Crimson spreads towards other Corruption/Crimson

[dsparadise]

Hello! Working towards that And Good Riddance achievement and I'm not really a fan of turning my whole large world into a grid and doing the whole spray and pray. Kinda feels like I'm cheesing and not really earning the achievement. I enjoy tearing through blocks with biome detection but I've reached the point where I think I have only a few blocks here and there of corruption/crimson. I'd like a method that helps me feel like I am working towards the goal and therefore earning it.

My thought was that it would be great if I could deliberately plant a corruption block and then watch as it spreads knowing that it spreads TOWARDS other corruption/crimson. So if I am in the middle of the world and it starts to spread towards the right, I go right and then work towards zeroing in on those pesky few blocks. Perhaps have some kind of evil fertilizer (crafted from regular fertilizer with rotten chunks/vertebra at a demon alter) that I could use to speed up the process. Leaving open the the possibility that I forget to clear this new batch if you want to have a consequence to playing with corruption/crimson.

I could also go for some kind of tortured divining rod item that I could hold and it could provide some kind of direction towards corruption (made with luminite) but that might make corruption clearing too easy.