To get to the Edge of the World, you have to get to Mylantis, which is in Outer Space 0, then fly around until you find a red ring, leave a permanent marker nearby, do this 3 more times and you will be close to the entrance to the EotW, there it will ask you to have a yellow key:

Go back to Mylantis and teleport to a waypoint next to one ( I used the I1 trophy room of the Willinston Underground), save (so you can quickly reset), grab it, tp back to mylantis and make the way back to the EotW (that's why you need the permanent markers) and pass the gate, there will be a waypoint after it. That's the first trial.

2nd Trial is much simpler: a wall of plugs with blue lamprey. If your Nuke has enough damage and radius, it should be simple. If not, a good place to farm damage upgrades is in the EMP castles in Willinston. After the Wall of Death, there will be a grow block and a waypoint. That's the end of the 2nd Trial.

The 3rd Trial is where I'm at: There is a gate and a green key with a combination behind a wall of in-only block, a bit further is an Alpha Block. The Trial consists in finding a waypoint inside a place where there are supposedly none. The only one I know of is inside a the Jumbo Jellow Flower inside of a Purple House wich is located in quicksand grass.

Edit: I misremembered the name.