Gloom

Gloom is a substance that drains the life of its victims. It appears in , and was unleashed when Ganondorf was resurrected underneath Hyrule Castle, nearly killing Link and drastically reducing his Life Gauge. Following the Upheaval, it was found in vast quantities in the Depths and around chasms on the surface.
Gloom has a similar viscous, ooze-like appearance to Malice - but whereas Malice was purple-black, Gloom was red-black. Gloom is also more potent and dangerous than Malice, as damage done by it can be permanent as shown by Ganondorf's attack on Link. Less severe exposure to Gloom was reversible, however only under certain conditions: activating or traveling to a Lightroot, eating something with the "sunny" effect such as food or elixirs cooked using a Sundelion or Sun Pumpkin, or remaining outside the Depths for long enough provided that Link is not being chased by Gloom Spawn or Phantom Ganon, where the sky turns red similar to a Blood Moon, will restore lost hearts at a rate of 1 heart per second.
== Enemies ==
=== Gloom Spawn ===
Gloom Spawn are arm-like tendrils that are made of gloom, and travel around with Gloom following them. Defeating the Gloom Spawn summons a Phantom Ganon. Moving a certain distance away from certain Gloom Spawn will cause it to de-spawn and leave Dark Clumps, without spawning Phantom Ganon.
=== Phantom Ganon ===
Phantom Ganon in is a Gloom infused creation of Ganondorf created from his own flesh and blood. Phantom Ganon can wield a variety of weapons including: Gloom Sword, Gloom Club, and Gloom Spear. Phantom Ganon will deal Gloom damage and will have a small pool of Gloom around him. Phantom Ganon serves as the boss of the fifth dungeon in the game but can be summoned upon defeating Gloom Spawn. Upon defeat, Phantom Ganon can drop two of four weapons; Gloom Sword, Gloom Club, Gloom Spear, and Demon King's Bow. The three melee weapons, when used by Link, will cause one heart of Gloom damage whenever an enemy is hit. the Demon King's Bow's damage will vary based on maximum number of hearts.
=== Depths Monsters ===
With the exception of Froxes and Flux Constructs, all monsters that appear in The Depths will be Gloom infused and deal Gloom damage. 
=== Ganondorf/Demon Dragon ===
When Link and Zelda first found Ganondorf at the Depths and awakened him, Ganondorf unleashed a stream of Gloom that not only crippled Link's right arm and shattered the Master Sword, but also permanently destroyed twenty-seven of Link's thirty Heart Containers. Link would have to collect Lights of Blessing to exchange for new Heart Containers.
During the final battle with Ganondorf, all of his attacks are Gloom infused and will deal Gloom damage. However, he can also unleash unique Gloom attacks, which will, if it hits him, destroy a single Heart Container, which will be irretrievable. Upon becoming the Demon Dragon, his entire body is coated with Gloom, which will cause Link to suffer Gloom damage so long as he walks on the scales outside of the four weak spots. The Dragon also releases Gloom blasts from his mouth that will once again permanently destroy a Heart Container if it connects. However, the game cannot be saved during the battle, so any permanently lost Heart Containers will be restored upon defeating Ganondorf and completing the game.
== Notes ==
* Sunlight, Lightroots, and Gloom healing foods will only restore the "maximum" hearts and does not recover the current amount of health. 
* When Gloom Spawn de-spawns, this will count as being killed/defeated and will not spawn until a Blood Moon occurs.
== Trivia ==
* Gloom could possibly be a form of blood magic, which is often considered a dark art. This would make sense due to the connection of Blood to Ganon in the past.
** In the Legend of Zelda: Breath of the Wild, and later during Tears of the Kingdom, when Ganon is at the peak of his power, a Blood Moon occurs and resurrects those loyal to him.
** In , after Ganon was destroyed, the minions of Ganon sought Link's blood to resurrect him, further linking Ganon to the concept of Blood Magic.