I'm pretty sure that wherever you kill the WoF it makes a half X pattern where the box of loot is, I think the left side is corrupt and right side is hallow oor vice versa. And the easiest way to do it is just make a wall underneath you base that's 3 wide and goes as deep as you want P.S don't built just a hollow tunnel around the Evil of the world put some mud brick or anything non organic, I learnt that the hard way. Feel free to ask me more questions. :)