Ending S - "The true god of Fear and Hunger"

The Knight's character specific S rank Ending can only be achieved in hardmode. In order to do so, the player must locate three torn scraps of a scroll that teaches a spell used to revive The Captain (Le'garde). The three torn scraps must then be used in the crafting menu to create the full page. All three pieces are hidden inside of Ma'habre. Once you have collected all three pages, go into your crafting menu and create the scroll. Use the completed scroll from the book section of your inventory, this will teach you the Spell of Rebirth. After obtaining the spell, visit Le'garde's corpse and keep interacting with it until given the prompt to the cast the spell. Once you select yes, the ending will play out.
 * Torn Instructions I is hidden inside the grand library within one of the pillars containing books on the ground floor in the second chamber. It will be in a pillar on the right side of the room.
 * Torn Instructions II is hidden in one of the bookcases next to the ladder that descends into The Enlightened One boss fight. It will be on the right hand side of one of the lower ladders closer to the abyss. You do not need to fight The Enlightened One in order to obtain the page. Once you have the page, simply exit the way you came back up the ladder to avoid the fight.
 * Torn instructions III can be obtained only in past Ma'habre. It is tucked inside the journal sitting outside of the stack of cages near the grand library. The cage room is located beneath the room housing a husk floating within a tank and connecting to the second floor of the grand library. This room housing the husk also has a ritual circle engraved in its floor in present Ma'habre.

Tips

 * You don't need to fight any monster. You can pretty much just run your way through the whole game, avoiding monster encounters until you get the torn instructions.

Trivia

 * This ending's artwork was based on an older concept art which showed Celeste's older design, implying that she was reviving Cahara.