Starcraft 2 Overseer
Zerg Unit Strategy Guide
|Body Class||Armored, Biological|
|Training Requires:||Overseer, Spawning Pool, Lair|
Overseers are the primary Zerg detection method, so can be used to spot burrowed, or otherwise cloaked enemies. They act as Overlords (and are created from them) but cannot be upgraded to transport units like the Overlord and lose the Generate Creep ability. Overseers are much faster than an Overlord as well, even before pneumatized carapace is researched.
Overseer Special Abilities and Upgrades
The Zerg Overseer gets two abilities aside from being a detector. Their Spawn Changeling ability can be used to effectively scout an opponent's base. Changelings can move and will not always be shot on sight. In fact, you can get a great look at the enemy base and unit composition there. The Overseer can spawn three, so they can be sent to different points on the map to learn about the enemy. Knowledge is power, especially in Multiplayer.
Their second ability, Contaminate is pretty simple. It halts all production at a targeted enemy building for a time. This is a good reason to take an overseer along with your attackers. You'll have a detector and a utility special to stop the enemy from making reinforcements. Of course, changelings can be sent out ahead of your attack to spot a good point to mount the offensive.
Overseer Uses in Multiplayer
Contaminate can be useful as you can get Overseers out fairly early and stop the enemy from upgrading very quickly. Halting all production can be helpful as it will prevent the enemy from fielding big units like the Terran Battlecruiser or Protoss Colossus by using it on the appropriate buildings. Larvae will not spawn at Hatcheries, and Chrono Boost and abilities of the Orbital Command will not work. It's worth noting that contaminate only works on unit production buildings and places like the Forge or Engineering bay where upgrades are researched. It won't stop towers like the Photon Cannon, Bunker, Spore/Spine Crawler or Missile Turret from firing. They're also the Zerg's only mobile detector and should accompany your army if you suspect your opponent is fielding Dark Templar, Ghosts, or Banshees. Also keep one near your mineral line to detect enemies. A few Hydralisks can bring down cloaked foes that way with ease.
Use the Changeling to get a peek at the enemy's unit formation just before attacking with your main army. This'll give you valuable information and allow you to assess the situation before moving in.