Lords of the Fallen

This Guide contains spoilers for main bosses, locations and NPC names

This is a missable achievement if you have proceeded into late game or if you kill the Lightreaper Boss before Upper Calrath

Doing Isaac's quest WILL lock you out for Kukajin.

Doing this achievement will reward you with the dark crusader class upon completion if you have not unlocked it yet.

This is my first guide so I apologise if it isn't the best.

Step 1 - After defeating the first boss of you game you must then DIE to the "Lightreaper" boss battle straight after this is first of many, after respawning at the vestige, re-enter the boss arena and you will go up the path exiting the boss arena, instead of going left/forward to proceed onward with the game turn right and follow the path at the end of the path will be an item on a body next to a big door, pick up the item "flayed skin" to begin this quest and spawn the umbral sigma/imprint needed to proceed

Step 2 - After proceeding through the game you will fight the Lightreaper again in Fitzroy Gorge near the Lower Calrath entrance YOU MUST ONCE AGAIN DIE making 2/3 deaths

Step 3 - until you reach Lower Calrath (Depot) upon entering the burning area after a very short path their will be a small broken wooden bridge that requires umbral form to proceed, enter the umbral realm and turn around their should be an blue umbral imprint for you to interact with use "Soul flay" by pressing RS to lock on and LT then RT to soul flay the imprint upon completion you will earn 2x "Umbral Scourring" and a "Wooden Dark Crusader Cross" this step is complete. If you missed this travel to the Depot/Vestige of Sebastian turn around cross the bridge on your right and imprint is on the left

Step 3 - Proceed through the game further until you enter the snow area of the game Fief of the Chill Curse continue until reaching the "Vestige of Svornil" once at this vestige turn around looking towards the gate, enter umbral realm and use soul flay on the "Umbral Imprint infront of you this will complete step 3 of the quest receiving x2 "umbral scourring"

Step 4 - At the "Vestige of Loash" continue and defeat the main beacon boss "Hallowed Crow" continue on the path once at the tower with the beacon in it after going up the tower to light the beacon (radiant ending) go down the tower instead, revealing an open area and go into the big arena and YOU MUST DIE to another lightreaper encounter this is the final encounter you will have to die. Return to the arena and proceed onwards drop down the ledge then go into umbral and on your right should be another umbral imprint, use soul flay to interact with it to complete this step.

Step 5 - After Defeating "The Sacred Resonance of Tenacity" boss instead of heading forwards towards the cliffs and pilgrim perch's upper area turn around and follow the path to go up the stairs to the Memorial area (Path of Devotion) or Vestige of Dieter (Needed for the merchant "Thehk-Ihir" quest) the vestige to this area is on the right from entering, proceed down the hill after the dog and archer you will find 4-6 Pilgrims praying towards a hill with a big Mace Knight on top (the unique item Anvil Hammer is on the hill) from the Anvil Hammer pick up turn around and enter umbral their will be another Umbral imprint facing the cliff edge interact with it by using soul flay and procced on down the hill progressing through the path of devotion (you can come out of umbral if you'd like while fighting the enemies but you need to go back in shortly).

Step 6 - After proceeding down around mid way the path of devotion you will find another hill with a few dogs around and an archer enemy on top, takes these out and be careful for the mimic item in the area after clearing out the enemies enter umbral and proceed through the big umbral door (if this is locked you have missed one of the 4 umbral imprints needed to open it) in the area and pull yourself across into the new area this is a boss arena where you fight Isaac interact with the umbral imprint using soul flay and defeat Isaac awarding you with "Umbral Tinged Flayed Skin"

Step 7 - Make you way back to the Defiled Sepulchre and return to the area near the first boss area where you picked up the original flayed skin, enter the umbral and interact with the door using the "Umbral Tinged Flayed Skin". Follow the path to collect the Paladin Armour set and sword (Pendant is found in Bramis Castle if you are interested for all pendants but this is not needed for the quest).

Step 8 - After killing all Main Beacon bosses Make your way back through Upper Calrath until you get to the "Lightreaper" boss again (there is a seed location nearby if you want to use it) YOU MUST DIE FOR THE FINAL TIME HERE. Return to the boss arena and you should now see a summon next to the boss door, summon Isaac and Defeat the L"ightreaper". id recommend before going into boss fight again go into umbral first and get to the ladder up and right of the boss door to destroy the umbral vestige that heals the lightreaper boss then proceed and after summoning Isaac, enter boss room and defeat the "Lightreaper". ISAAC DOES NOT HAVE TO SURVIVE THIS FIGHT JUST NEEDS TO BE SUMMONED SO DONT WORRY IF HE DIES.

Step 9 - Achievement Unlocked and Dark Crusader Starting Class Unlocked

I tried to include as much info as i could and if i missed anything or any questions feel free to ask.
This is my first guide but i hope it helped.

Enjoy

here's a video guide if the written guide isn't your thing