The Mass Extractor is a structure common to all 3 factions. It provides a steady flow of Mass for your economy but may only be constructed on designated points called "mass deposits". Mass extractors tend to dictate the flow of battle early game, but are often less important late game when mass conversion becomes feasible due to a powerful energy supply.
The mass extractors of all factions are fundamentally the same in cost, health and output, varying only in design. The UEF mass extractor can be upgraded with ground and air defences, packing several times the firepower of regular ground units, allowing it to fend off small assaults.
Lone mass extractors are usually very difficult to defend and easy to destroy; bombers and gunships can severely damage a mass extractor before help arrives. Even when deployed close to a base, late game assaults can quickly annihilate an unprotected mass extractor. Noah Unit cannons, Space Temples, and long range artillery are all excellent methods of disrupting the enemies mass flow.
An excellent strategy for defending your mass extractors is to expand your base, or build forward bases, around your mass extractors, and surround them with PD's and AA's. If you're a cybran, you can also build a Recycler near your mass extractor. That way, the enemy will most likely send air units at you, given the fact that you have enough anti-air near the extractor, you shoot them down, and then reclaim the mass. You would also be wise to consider building 3-4 shields to defend from artillery fire.
Another way to defend a mass extractor (or, using this method, multiple extractors - preferrably), is to use a UEF Experimental Shield Generator. Seeing as they can keep an entire base covered (at the expense of energy), it would be logical to use them to defend multiple mass extractors that are a good range apart from each other. However, there is always the threat of enemy units passing under the shield from a position away from a mass extractor, making it only useful for defending against artillery and ranged attacks.
Cybran Shield Generators are penetrated by every shot, and Illuminate shields have a chance of being penetrated. Although the damage is very much reduced from the shot, given the fact that it has gone through 1+ shields, it will still deal damage nonetheless, making it ideal to keep a few engineers around to keep the mass extractors alive.
Assuming the enemy decides to ACU rush you, Mass extractors will be a primary target for them. For this reason, you should always keep a few units/PD's online near mass extractors to damage, or possibly even destroy any ACU's that come into range.
Late-game, Mass extractors become less and less useful, as Mass Converters come into use due to energy becoming more easily accessible. It would be wise to use this to your advantage, by attempting to take any mass extractors away from a hostile base, as the enemy will likely not care for losing a few extractors. Just more free mass for you.
All mass extractors were modified in patch 1.26
New patch 1.26 mass extractor 100 mass, 250 energy, 25 sec (half old cost)
Veterancy Mass/sec HP XP to Time to
Rank Next level Next level
0 0.6 3,500 12 1 min
1 0.8 4,125 24 2 min
2 0.9 4,750 48 4 min
3 1.2 6,000 96 8 min
4 1.8 7,500 192 16 min
5 2.4 10,000