The Labyrinth is a dungeon unlike any other in Path of Exile. It is filled with perilous traps, valuable secrets, tricky puzzles, and objectives that may require you to do things across several areas. To gain access to the Labyrinth, you must complete the six prerequisite trials that are scattered across the first three acts. A portal to the Aspirants' Plaza will then appear in the centre of the Sarn Encampment, and it is in the Aspirants' Plaza that all versions of the Labyrinth can be reached.
Best each of the six trials and you can enter the Aspirants' Plaza via the Sarn Encampment.
Successfully navigating the Labyrinth ultimately leads to a sequence of fights with the Labyrinth's creator, Izaro. Failure to survive the Labyrinth means starting again, so be careful where you step. If you manage to make it to the end, you'll be rewarded with treasure, an opportunity to enhance an item, and the ability to select your Ascendancy class.
There are four versions of the Labyrinth, each with a different set of entry requirements, and each reward you with two Ascendancy points upon completing it for the first time. Unlike most areas in Path of Exile, the Labyrinth's structure does not change greatly between runs during the same day, but once a day the layout is randomised. If you get very good at running the Labyrinth, you may make it to the leaderboards. The fastest time each day for each Labyrinth is awarded a prize. Some players make builds solely optimised to run the Labyrinth, however, so it can get very competitive.