A guide on how to get the secret achievement Destroyer of Worlds.
How to Obtain Destroyer of Worlds Achievement
This guide will contain spoilers for the end of the game so be warned!
This achievement is only available in the end-game, so you must unlock the final dungeon before you can continue.
You must first enter the Mysterious Mafia Base, which is unlocked after delivering the Laser Pointer to Mayor Onion. The entrance can be found behind this tree after talking to Old Man Lemon.
Continue left until you reach this room.
Then continue through the left door, where Turnip Boy is shown in the screenshot, and continue to the door below in the following room.
You will find yourself next to a ladder. Use the ladder, and then take the one in the following room to get to the third floor. Then continue through the doorway into the final room.
Before you now stands a nuclear warhead. To get the achievement, you must hit the nuke 3 times with your shovel to detonate it.
Now you have completed one of the rarest achievements in the game, congrats!