Azure Nebula
From Star Trek: Theurgy Wiki
The Azure Nebula was an interstellar cloud of matter, stretching into both Federation and Klingon space. Since sensors and other systems functioned poorly in many nebulae, the Azure nebula was used multiple times by starships in attempts to gain strategic advantage in evading or avoiding conflicts.
In 2381, the USS Theurgy escaped into the Azure Nebula following the catastrophic failure of their mission at Starbase 84. Inside, the crew took time to assess damage and provide repairs to the damaged vessel.
Explosive Gas
Large pockets of sirillium gas were located across the entire Azure Nebula meaning starships had to be careful in navigation. One use for sirillium was as a warp plasma catalyst and as a gas, it could also be used to boost the efficiency of deflector shields. However, as a volatile element, it could also be used for defense and subterfuge.
In 2293, the USS Excelsior travelled through the nebula to rescue James T. Kirk and Leonard McCoy. When the ship encountered a Klingon vessel, the Excelsior ignited the nebula's sirillium gas to disable the battle cruiser.
