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3 Gate Sentry Expand (vs. Zerg)

From Liquipedia StarCraft 2 Wiki
This strategy is for a previous expansion of the game.
[e][h]Protoss3-Gate Sentry Expand
Strategy Information
Opening, Mid-Game
Popularized by:


The 3-Gate Sentry Expand relies on fast, accurate Forcefields during early battles, without these you will not be able to use this build effectively against opponents who mass Speedlings. Another important skill is being able to not so much count the Sentries themselves, but to count the number of Forcefields you have available at a glance. This is extremely important as the number of Forcefields at your disposal determine how aggressive you can be out on the map.

This build masses Sentries not only to defend and repel any early aggression, but also to harass any attempts by the Zerg player to take a third base.

Your setup and army composition when expanding.

Build Order[edit]

Basic Build
  • 9 Pylon (Scout)
  • 13 Gateway
  • 15 Assimilator
  • 16 Pylon
  • @100% Gateway: Cybernetics Core
  • @100 Minerals: Zealot
  • @75 Minerals: Assimilator
  • @100% Cybernetics Core: Sentry, Warpgate Research
  • 22 Pylon
  • @50 Minerals, 100 Gas: Sentry
  • @300 Minerals: 2 Gateways (2)(3)
  • @100% Warpgate: Convert Warpgates
  • @400 Minerals: Nexus
  • @150 Minerals (constant Probes/Pylons/Sentries): Forge
  • @150 Minerals (constant Probes/Pylons/Sentries): Gateway (4)
  • @100% Nexus: Assimilator (3)
  • @100% Forge: Photon Cannon At Expansion, +1 Weapons
  • @100% Photon Cannon: Begin “Shark Mode”


  • With the scouting probe, the first thing you want to check is whether they are going for a Speedling Expand. If they are not Speedling Expanding, focus on blocking the Hatchery with your Probe and use your judgment to decide whether or not to build your 16 Pylon in a position that blocks the Hatchery from being placed.
  • If they are not Speedling Expanding, it may also be beneficial to build a Stalker instead of the first Sentry and to then use the Zealot/Stalker combination to poke at the Zerg's expansion. This is especially beneficial if you block the natural Hatchery with a 16 Pylon as it will become very difficult for the Zerg player to kill this Pylon without over-committing to Zerglings - this will put them behind economically in the short-term.
  • If they are going for a Speedling Expand then you could use the 22 Pylon to block the Hatchery. However, it will be quickly killed if the Zerg makes more than 2 Zerglings, so it probably is not worth it.

"Shark Mode"[edit]

Once you have a few Stalkers and your first Photon Cannon is done, it’s time to start moving around the map. Make sure you leave a blocking Zealot at the top of your ramp (and also at your natural if you were able to create a choke). The first thing you want to do is to clear out scouting Zerglings and Overlords, thus darkening the Zerg's vision of the map. Taking control of Xel'Naga Towers with Zealots is a good option as Zerglings are very cost-inefficient against them, forcing Zerg to commit units to retake them.

You should mostly be warping in units at your base. Every time you warp-in another round of units, your army should return to your base, add those to your army, and then move out again. The overall effect of this army movement is to create an atmosphere of uncertainty for the Zerg; when you challenge them for map control, they need to build units instead of Drones in case they get attacked. This slows down their economy. This form of pressure is called “Shark Mode” because your army is like a shark: if you stop moving, you die. If you do not do this, the Zerg player will be free to Drone and crush you with his macro.

During this time, you should also be trying to figure out which mid-game tech your opponent will focus on: Muta, Roach, or Baneling? A general rule is that if you see many Speedlings, expect Muta or Banelings. Only expect Roaches if you see Roaches. Mass Spine-Crawlers on only two bases can also be an indication that Mutalisks are being built. You should also be trying to figure out when the Zerg is going to take their third base; denying their third base for as long as possible is very important as the Zerg will get massively ahead of you economically if you let them take it too early.


  • While sharking, make sure your army is always hugging a wall-in case of a surprise ambush. This will mean that less Forcefields are needed to prevent a Zergling surround.
  • Have a Probe with your units at all times. This will give the illusion that you want to throw down a proxy Pylon, making it seem even more like the Zerg player needs to commit to making units in order to defend.
  • It can be useful to have a single Zealot walk just ahead of your army. This will also help to prevent ambushes.


vs. Roach Mid-Game[edit]

This is the standard Zerg mid-game play. Unless you scout otherwise, this is what you will normally do in most PvZ games. Starting from the beginning of "Shark Mode" and assuming both constant Probes and Pylons:

Basic Build
  • Robotics Facility After A Few Stalkers.
  • Whilst Robotics Facility Building: Assimilator (4)
  • @100% +1 Weapons, +1 Armor
  • @100% Robotics Facility: Observer, Robotics Bay
  • @100% Observer: Immortal
  • @100% Robotics Bay: Colossus (Chrono), Extended Thermal Lance
  • @100% Colossus: Third Nexus (Wall-Off With Pylons/Cannons If Possible)
  • Build Your 5th and 6th Assimilators In Time With Third Nexus Finishing
  • When Gas Permits It: Twilight Council
  • @100% Twilight Council: Blink Or +2 Weapons.
  • When Gas Permits It: Blink Or +2 Weapons (Whichever Wasn't Chosen First).
  • @100% Nexus: 4 Additional Gateways (Add To Wall-Off If Possible)

While all of this is happening, "Shark Mode" continues. Your army never stops moving and growing in size, except if the Zerg has a huge army moving around. In that case it’s okay to stay home and turtle behind Forcefields since you know he’s not pulling ahead in Drones. You warp-in constant Stalkers for the most part but at some point you will run low on Gas so you will spend some time warping in Zealots instead. Gas expenses need to be balanced around constant chronoboosted Colossus production.

Once you have 3-4 Colossi, it’s time to begin pushing. This is around the time when the income from your third base kicks in.

Note: In the pre-Colossus period, you need to avoid the “cut his army in half, kill the closer half” strategy that you might use against Terran. Because Sentries are so easily sniped, it’s better to place Forcefields so that you are never fighting more than a quarter of the Roach ball, as any more than that can quickly focus down your Sentries if the Zerg player is paying attention. This strategy can easily fall apart if you have to rebuild more than a couple of Sentries due to their gas intensity, so the main focus should be keeping the most Sentries alive rather than killing the most Roaches.

vs. Mutalisk Mid-Game[edit]

If you’re getting harassed by a ton of Speedlings, you can guess Mutalisks and go for a 6gate +1 timing-push. If you guessed wrong, you can go back to playing vs. Roaches since the mass Speedlings will slow your opponent down just as much as the 6gate slows you down. If you didn’t figure out that he went for Mutalisks until you made a Robotics Facility already, then you can use Observers to help defend vs. harassment (use them to see the angle the Mutalisks are coming from) whilst teching to Blink. iNcontroL likes to get DTs to harass against this style as it forces the Zerg to build Overseers (preventing gas from being used on Mutalisks) and also allows for a strong Stalker/Sentries/Zealots/Archon composition against Muta/Ling. There are no strict timings other than starting the Twilight Council as soon as you know they went Mutalisks (assuming you missed the timing to skip the robo and go for a 6gate +1 timing-push) and trying to push before the Zerg player can fully switch to Roaches.

vs. Zergling/Baneling Mid-Game[edit]

You need to turtle very hard while following the same general road map outlined above in "vs. Roach Mid-Game". Against this style of play you will never be able to leave your base until maxed as Banelings can kill your Sentries far too quickly for it to be worth it; keep expanding defensively until you have the perfect death-ball with Stalker/Sentry/Colossus. As long as you sim-city well with Gateways and Cannons, you should be immune to ground-based counter-attacks or back-stabs.