Support/Aerial transport Synth
Advisor pods are large, white Synth ships used by the Combine as escape vessels, transportation, and incubation containers for Advisors. They have a heavily armored, featureless hull bearing the Combine emblem on its surface. Each pod is marked with a code printed on the side - for example, 314 URB-LOC 0017. The Synth is mostly hollow, allowing it to house an Advisor in the larvae stage of its metamorphosis in a transparent casing. The pod is able to close the retractable canopy lip with its legs to provide complete protection, using this state when in flight. Though they are never seen acting in combat, Advisor pods appear to have the same "Belly Cannon" possessed by Combine Gunships.
They are first seen in Episode One when Gordon and Alyx witness a pod transported up through the Citadel with an Advisor housed inside. At the end of the game, many pods are seen fleeing from the Citadel moments before its destruction. In Episode Two, an Advisor pod can be seen being transported along with a battalion of Combine soldiers and Striders. A crashed Advisor pod is also seen later on, having released its Advisor occupant several hours prior to Gordon and Alyx's arrival.
Behind the scenes
In Episode Two, the developers originally used flying Advisor pods, much as how they flew from the Citadel in Episode One, to show how Advisors traveled with Combine forces. However, this gave the wrong impression that Advisor pods were self-powered flying crafts capable of being piloted around rather than simple emergency escape units. The flying element was cut and replaced with an Advisor Platform transporting an inert Advisor pod.
Combine convoy en route to White Forest, escorting an Advisor pod on an Advisor Platform.
Crashed pod in the Outlands.