So, remember how I asked about how to keep the corruption and hallow away from my base, and make the base hardmode-proof? Well, I took your suggestions. Dug a couple of nice wide pits all the way down to hell on either side of the base. Used unchangeable blocks as a new "floor" so I wouldn't fall all the way down by accident. Rebuilt the outer wall of the base with a three-block-thick layer of dungeon brick. Added trapped entrances with plenty of pressure plates, dart traps, and wire.
Went down to the underworld, killed the WoF without undue difficulty thanks to all the buffs I brought with me. I Magic Mirror my way back up...
Corruption literally right outside my door. The new zone decided "fuck your hours of preparation" and spawned inside my perimeter. I had been back less than 10 seconds when one of the corrupt hardmode worms went tearing through my base, killing an NPC, and followed by wraiths. Werewolves are beating at my door and taking virtually no damage from the traps, and purification powder can never change it all in time. I have never hated this game before, but right now I sure do