The third level delves the player deeper and to the lowest floors of the shaft. The player loses his armaments in a weapons containment field, and for a large portion of the level the player must run from Combine soldiers while solving puzzles using crates. During this segment of gameplay, the player will stumble across the impressive core of the reactor that receives the energy of the plasma stream. It is apparently used to power a Combine Portal reactor (similar to the one at the top of the Citadel, seen at the end of "Half-Life 2"). The player arrives just in time to see a portal form to an unknown (and apparently barren, except for antlions) planet. The planet is also seen as a holographic projection or on screens throughout the Combine base. Minerva says that it is unconquered and unexplored by the Combine, although several Dropships are seen coming through the portal.