Corrupted Essence
Giga plague
Stage Tower of Fate: ????
Theme The Battle Within
The Corrupted Essence is the final boss of Plague of Shadows and the final form of the Serum Supernus. It represents Plague Knight's perfect self with the power of the Ultimate Potion.


The Corrupted Essence appears a large, three-eyed and winged being in the likeness of Plague Knight. It rides on top of a metal orb resembling a cauldron.


Spoiler warning!
This article contains plot details about an event that occurs later in the game.

The Corrupted Essence is the second form of the Serum Supernus after the Plague of Shadows, and the incarnation of Plague Knight's Essence overpowered and out of control. Once defeated, the Ultimate Potion finally stabilizes and Plague Knight regains his senses.


The Corrupted Essence can be damaged by hitting the flashing spot inside its mouth. It opens its mouth to attack Plague Knight or after attacking the device it is standing on is damaged after being exposed by attacks.

It can attack by:

  • Shooting projectiles
  • Tackling Plague Knight
  • Bouncing, trying to smash Plague Knight
  • Creating a lot of explosive sprites shaped like Mona and with an exploding radius similar to the Big Boom.



  • Although not clearly stated, this battle takes place in Plague Knight's mind.[1][2] It can be interpreted as Plague Knight fighting against his wish for more power.


  1. Twitter post by Yacht Club Games
  2. Hinted in the name of the boss theme, "The Battle Within"
Plague of Shadows Characters
Main Characters: Plague KnightMonaBlack KnightShovel KnightThe Enchantress
The Order of No Quarter: King KnightSpecter KnightTreasure KnightMole KnightTinker KnightPolar KnightPropeller Knight
The Wandering Travelers: Shovel KnightReize SeatlanBazMr. HatPhantom Striker
Guest Characters: Madame Meeber
Potionarium: MagicistHedge PupilMail MinionPercyOolong
Armor Outpost: ChesterTroupple AcolyteLeoPeacock GentDollyAirship Enthusiast
Hall of Champions: Head GuardCultured FellowPatron
Other Characters: Troupple KingTroupplePlague of ShadowsCorrupted Essence
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