Babylon 5: A Call to Arms

Galen, the Technomage, appears to Sheridan because the Technomages have been watching the galaxy for decades and are aware of the Drakh threat. Daltron 7 was destroyed by the Drakh as a prelude to their attack on Earth, and Galen's visions serve as a warning of what is to come. He also reveals that three individuals will meet Sheridan at Babylon 5 to aid him, though he orders Sheridan not to reveal his mission to anyone.

Earlier in the voyage, Galen visited Sheridan in a dream showing a ruined world, foreshadowing the discovery of Daltron 7's destruction.

Dureena is a skilled thief from Zander Prime, a world destroyed during the Shadow War. Her unique set of skills, stealth, lockpicking, and guile, proves crucial in locating the master control hub of the Shadow planet killer during the battle. She is also a refugee who initially blames Sheridan for her world's destruction, but learning about the Drakh's plans shifts her perspective and makes her a willing participant in protecting Earth.

In her dreams, Galen warns Dureena to choose her targets carefully when the moment to act arrives, hinting at her role in the planet killer's hub.

The Drakh possess a Shadow planet killer, a weapon of planetary scale capable of destroying entire worlds. They used it to annihilate Daltron 7 less than a week before their intended attack on Earth. The weapon is powered by Shadow technology and features a master control hub that, when destroyed, causes the device to self-destruct prematurely.

Galen's vision of Daltron 7's destruction foreshadows the discovery of the planet killer and its devastating capabilities.

Excalibur channels energy from its entire hull into a single devastating burst, using Vorlon-Minbari technology reverse-engineered from the White Star design. This immense firepower comes at a cost, the ship requires about a minute to cooldown before it can fire again, leaving Excalibur temporarily underpowered and vulnerable during that recovery period.

The weapons test demonstration explicitly shows the tradeoff between firepower and the recovery cooldown period.

Lionel Drake is a Mars citizen who demonstrates Excalibur's capabilities during the firing range test. However, he is revealed to be an informant feeding the Drakh crucial details about Earth's defenses. His betrayal allows the Drakh to anticipate Earth's movements during the invasion. Garibaldi catches up to the shipyard and deduces Drake's treachery, subduing him to extract information about the Drakh fleet.

During the test, Drake showcases Excalibur's capabilities, providing him insider knowledge of the ship's systems and vulnerabilities.

During the battle, Dureena uses her guile to locate the planet killer's master control hub. Victory suffers critical damage to its weapons systems, and in a desperate move, Captain Anderson orders his crew to drive Victory directly into the control hub. This triggers the planet killer's premature activation, causing it to self-destruct and destroy most of the Drakh assault fleet.

Sheridan's warning to EarthGov to mobilize the entire fleet builds toward this climactic confrontation at the planet killer's hub.

Although the planet killer is destroyed and most of the Drakh fleet is eliminated, a remnant Drakh fleet escapes into Earth orbit and releases a sinister black gaseous weapon, a biological weapon engineered by the Shadows. This plague can adapt to human physiology and threatens to wipe out all life on Earth within five years if no cure is found.

The victory is immediately undercut by Lochley's report that Earth has been infected, transforming the celebration into a new existential crisis.

After Earth is contaminated with the Shadows-engineered plague, Sheridan transforms Excalibur into a dedicated research vessel to search the galaxy for a cure. He assembles a cadre of top scientists and experts from across galaxies to find some breakthrough, any technology or method that could reverse the plague's effects and save humanity from extinction within five years.

The desperate situation on Earth following the plague discovery necessitates the transformation from warship to scientific exploration vessel.

The Drakh are allies of the Shadows who were defeated during the Shadow War. Their revenge against humanity is part of a broader retaliation against those who opposed the Shadows. They possess Shadow technology and continue their masters' work, using the planet killer attack on Daltron 7 and Earth as a prelude to wiping out human civilization.

Galen warns that the Drakh loom on the horizon and plan to attack Earth, continuing the Shadow legacy of destruction.

The Drakh are allies of the Shadows from the previous Shadow War. Even though the Shadows themselves are gone, the Drakh remain and continue their masters' work. They possess Shadow technology, including the planet killer weapon, and use Shadows-engineered biological weapons. Galen notes that the Technomages have watched the galaxy for decades and are aware of the Drakh's return.

The Drakh's use of a Shadow planet killer and Shadows-engineered plague directly connects them to the defeated Shadow civilization.