- Hail to Sithis, blood's drop on blade's edge.
- Before you, nothing. Behind you, the Void.
- Catalyst, agitator, many-fanged maw.
- Whisper your need to the Scales.
- — Inscription found on an Argonian blade
The Shadowscales are an order of Argonian assassins originating in Black Marsh. Argonians born under the sign of the Shadow are taken at birth and offered to the Dark Brotherhood where they are trained in the arts of stealth and assassination. Any Shadowscale who lives to come of age is accepted into the Dark Brotherhood as a full member of the family. They may also leave the Brotherhood and return to Black Marsh to serve the Argonian people. They act with impunity there, and some serve as personal assassins to the King of Black Marsh.
Shadowscales follow the same five tenets traditionally followed by members of the Brotherhood, although they are a distinct set of rules. For example, a Shadowscale cannot kill a fellow Shadowscale even if they are not members of the Brotherhood. However, breaking a tenet of the Brotherhood invokes the Wrath of Sithis, and forgiveness is possible if the family member survives the encounter. If a Shadowscale breaks a tenet, it is viewed as treason and the perpetrator will be put to death. This is usually carried out by the Argonian Royal Court, who will send an unaffiliated assassin to carry out the execution.
Many Shadowscales were opposed to the formation of the Ebonheart Pact in the Second Era, with some even turning traitor and fleeing Black Marsh. However, the Shadowscales fought on the Pact's side during the Aldmeri Dominion invasion of Shadowfen in 2E 582 by liberating the town of Murkwater.