Assimilator

The Assimilator is a Protoss building used for harvesting Vespene Gas. Although materials are usually warped in from Aiur, Vespene Gas is still required for these materials to be produced and the creation of warp rifts.

An Assimilator must be warped in on top of a vespene geyser before Probes can collect vespene gas from it, packaging the gas for collection.

StarCraft II
The Assimilator remains much the same as its predecessor in StarCraft II.

Restore Gas
If the Assimilator is depleted, at a cost of 100 minerals, the player can gain 600 Vespene gas. Doing so prevents gas collection for 45 seconds. The player must balance their need for gas against the immediacy of this need. "Restore Gas" can be used any number of times.