To get the secret or true ending in Darksiders 3 you really don’t have to do much. All you will need to do is find the secret boss in the Scar area and choose a few specific actions, to find this boss go to The Lowlands Vulgrim point in the scars and backtrack across the magnetic wall and look for a vortex that you can use with the storm hollow, in the upper area just take the second left to find an elevator that will take you to the secret boss. Here you will have to choose to kill or spare, YOU HAVE TO KILL HIM to have access to the secret ending, after you have done with the secret boss you will have to use a serpent hole to go to The Lord of Hollows Chamber, here you will see a unique cutscene where you will once again have to choose to kill or spare… This time YOU WANT TO SPARE HIM. Now go on and complete the game to get a unique ending.