The thing is, we already have a Clentaminator that sweeps out to past the screen's edge. What might help with complete purification would be detection -- something that would highlight infected blocks even when they're buried in stone.One thing I personally would love to see added to the game (and I really hope leinfors sees this) is something to do with purification. I would love to see the player get a special reward from the dryad after purifying the entire world. Something really really cool that would incentivize doing so at least once in a players terraria career. Then at least we could have SOMETHING to do after Moon Lord is defeated. I agree that the endgame of terraria is a bit of a double edged sword on the fact that you do beat the moon lord and get all this amazing loot, but unfortunately have nothing to really use it on.