Plasma Beam

The Plasma Beam, found exclusively in Quake II Mission Pack: Ground Zero, is functionally equivalent to the Quake's Thunderbolt, in that both are powerful sustained hitscan weapons with pinpoint accuracy. However, the Plasma Beam reaches much further with its beam than the Thunderbolt with its lightning, to the point where its range is practically infinite.

Strategies

 * The Plasma Beam uses two cells per shot, and does less damage per tick than a Hyperblaster bolt (15 vs 20), making it an absolute ammo hog in exchange for ease of aim. Use the Hyperblaster on slow targets and in close range, and if you can't lead your shots well enough to hit agile or airborne enemies, consider the Plasma Beam instead. Even then, the Chaingun might be a better choice, as bullets are more expendable than cells.
 * While the Plasma Beam's extreme range allows it to snipe, the Railgun is much more ammo efficient, deals double damage to unaware enemies, and doesn't require tracking targets, making it the superior sniper.
 * In multiplayer, the benefits of a hitscan weapon much more effectively outweigh the ammo-hungry nature of the Plasma Beam. Use it like you'd use the Thunderbolt or Lightning Gun in other Quake games, with the benefit of not needing to worry about how far away you are from your target.