Gloom

is a substance in.

Characteristics
TotK: is very similar to Series: and is produced by TotK:. When TotK: comes into contact with it, it temporarily reduces his maximum NaN Hearts. Hearts that have been depleted by Gloom will appear to be gray and broken, allowing them to be distinguished from damage taken from other sources. The NaN Hearts damaged are always whole NaN Hearts, meaning half or quarters of a TotK: cannot be reduced. If TotK: has any temporary NaN Hearts prior to taking TotK: damage, they will all disappear. When TotK: eats NaN Meals that grant temporary NaN Hearts, they will restore the NaN Hearts he has lost to TotK:, albeit unhealed. If TotK: dies after TotK: has reduced his TotK: to less than five NaN Hearts, being revived by a TotK: will restore to having 5 hearts as maximum and also filled.

During "TotK:", TotK: is shown to have the ability to permanently destroy NaN Hearts, leaving TotK: with only three in his TotK:. TotK: demonstrates this again during their battle in TotK:, but only a single TotK: is lost at a time. After TotK:'s TotK: has been reduced to a single TotK:, the TotK:'s perma-gloom attacks will begin to deal regular damage instead.

TotK: saps the strength of individuals upon touching them, in some cases leaving them sluggish and unable to move. Being on the TotK: or the TotK: allows TotK: to recover from losing NaN Hearts to TotK:, at a rate of one TotK: per second. However, being in the TotK:, fighting TotK:, and facing TotK: all prevent TotK: from recovering. These factors can be mitigated by standing beneath a TotK: or eating TotK: made with a TotK: or TotK:. Sleeping in a TotK: also restores NaN Hearts lost by TotK: and fills them.

NaN Enemies in the TotK: are frequently wreathed in TotK:, and they will similarly reduce TotK:'s maximum health when attacking him. In this case, they are capable of dealing multiple NaN Hearts-worth of TotK: damage. Elemental damage from NaN Arrows will deal both regular and TotK: damage. TotK:'s attacks are also able to deal higher amounts of TotK: damage.

Trivia

 * The permanent gloom damage during the final boss cannot reduce Link's Life Gauge to below 1 heart, it will instead do normal damage.
 * The Fairy can recover permanent gloom damage during the final boss when Link gets killed with fewer than 5 hearts.