When it comes to traveling across planes there is a slight requirement. Each plane requires a quest item to access it. For example to go from Surface to Labyrinth, you need to kill a Labyrinth Fiend on Surface to get the Key of Labyrinth to drop, from there you can use the traverse option in the map movement section to select the Labyrinth plane and move to it.
New planes, means new maps, means new locations and monsters. Some Planes like Shadow Planes, Hell and Purgatory make the monsters even stronger and can make you, the player, weaker. This means you need to focus on your gear through crafting and enchanting to overcome the new challenges.
The other benefit to traversing is that you can get better gear from drops, assuming your looting skill is high enough.
Each plane will allow you to get better gear – all randomly generated – through killing monsters. Each plane caps the level of gear you can get with Purgatory being level 300 crafting gear.
When you are ready to traverse you can click the “Traverse” button at the bottom of the map movement options. You can see the modal to the right or bottom for mobile.
For mobile players you will have to select Map Movement from the main actions sections and then select the traverse option under the map.
There is a 10 second movement with traversing.