I'm reasonably close to the point where I would try to trigger hard mode, and I'm making some preparations. As far as I understand, once I trigger hard mode, corruption and hallow will spread quickly.
I'd like to prevent my home base from becomnig corrupted/hallowed, what do I have to do to ensure that? I've created an air gap around the home, but is that enough? From what I read there are also enemies that can spread corruption, how can I prevent those from infecting my home?
Best Answer
There are no longer enemies that spread corruption, crimson, or hallow. So, what you need is a 4 tile barrier made of pretty much anything besides stone, sand, ice or dirt. The favored method is by making a quarantine tunnel all the way around you base. My preferred method is as follows:
Start with a 4 block wide tunnel. You can use the Ruler if you're super paranoid.
While that tunnel itself is perfectly fine for hardmode protection, I like to line my tunnels with Some type of brick. This has multiple advantages such as thorns no growing in your tunnel (since the corruption can't spread over the bricks themselves), it looks nice and clean, and most importantly, it is a visual reminder to you and other players not to build there. Keep in mind that these bricks are in addition to the 4 air tiles
Now just continue with this tunnel all around you base. Give yourself plenty of room so you can keep your farms within the quarantine zone and so you don't have those hardmode enemies spawning right at you doorstep.