Scouting Guide

Information is the whole game

Here’s what separates a Diamond player from a Masters player more than anything else: the Masters player knows what’s coming. Not because they’re psychic, but because they scouted, saw two gases before a natural expansion, and recognized that means early tech aggression. The Diamond player didn’t scout, assumed a standard game, built 10 extra Drones, and died to a Void Ray/Zealot all-in at 5:00.

SC2 is a game of incomplete information. You can’t see what your opponent is doing unless you actively go look. And your entire strategy should change based on what you find. Going for a greedy third base? That only works if your opponent isn’t about to hit you with a timing attack. Building Carriers? That’s great unless they’re already making Corruptors. Every good decision in SC2 is a response to information. Without scouting, you’re guessing. Sometimes you guess right. More often you don’t.

The early worker scout

The first piece of information you need is where your opponent spawned. On four-player maps, this matters a lot. You send a worker out between 13 and 17 supply (depending on your build) to find their base. Protoss players typically send a Probe at 14-15 because it doubles as a pylon scout, potentially placing a forward pylon for proxy Gateway plays. Terran sometimes sends an SCV to scout after starting the Barracks. Zerg uses an Overlord, which is free, but slow.

What you’re looking for with the worker scout is simple: what did they build first? You want to see their gas timing and their first production structure. If a Protoss has two gases and a Cybernetics Core but no Nexus building at the natural, that’s aggressive. They’re investing in tech, not economy. If you see a Nexus already started and one gas, that’s a standard macro game.

Against Terran, check if the Barracks is in their base or at your front door. A proxy Barracks means Reapers or Marines in your natural within the first two minutes. Against Zerg, check the Pool timing. If the Spawning Pool is already building when your scout arrives and there’s no Hatchery at the natural, that’s a Pool First opening. You should expect early Zerglings.

First unit scouts

After the worker scout, your first combat unit takes over scouting duty. For Terran, that’s the Reaper. It’s fast, it jumps cliffs, and it arrives at the enemy base around 2:00-2:15. The Reaper is one of the best scouting tools in the game because it can see the entire base, poke at workers, and get out alive. While it’s there, check: how many gases? What buildings are under construction? Is there a wall at the natural? Is the expansion started?

Protoss usually scouts with an Adept or the initial Stalker. An Adept shade into the enemy base at 3:00 gives you vision of their production without committing the unit. Alternatively, a Hallucinated Phoenix from a Sentry can fly across the map at about 4:30 and see everything. This is one of the best scouting tools in the game and costs zero real units. Just 75 energy on a Sentry. If you’re a Protoss player and you’re not using Hallucinated Phoenix scouts, start today. I’m serious. It changes how you play.

Zerg scouts with Overlords. Your first Overlord should be pathed toward your opponent’s base from the start of the game. On most maps, it arrives around 2:30-3:00. Park it at the edge of their natural to see the expansion timing, then move it in around 3:30-4:00 before anti-air comes online. After Lair tech, morph an Overseer for changeling scouts that give free, risk-free vision inside their base.

What to look for when you get inside

Scouting is useless if you don’t know what you’re looking at. Here’s a quick breakdown of the things that matter most.

Gas count. This is the single most telling piece of information. Gas means tech. One gas is standard. Two gases before a natural expansion means something aggressive or techy is coming. Zero gas at 2:00 usually means a very economic opener (or a Barracks-only all-in from Terran, which is a very different situation). Pay attention to gas timing because it tells you how fast expensive units and upgrades will arrive.

Tech buildings. Seeing a Dark Shrine means DTs are coming. That’s not a guess, it’s a guarantee. If you see a Starport with a Reactor, expect double Medivac drops. A Twilight Council means either Blink or Charge is being researched. Robotics Bay means Colossus or Disruptors. Each building tells you which units are about 60-90 seconds away. If you can identify the tech path, you can start your counter-tech before their units even finish.

Expansion timing. Is their natural base started? Finished? Is there a third? A player who hasn’t expanded by 3:00 in a standard game is spending that money on something else, and that something is usually aggression. If they have a fast third, they’re being greedy and you have a window to punish.

Army size and position. If you see their army moving out, that’s a push. Pull your scout back and prepare at home. If their army is sitting in their base with no expansion, they’re about to hit you with everything they have. If their army is small relative to the game clock, they’re investing in economy and you can be aggressive.

Worker count. Hard to count exactly, but you can eyeball it. A player with a lot of workers at their natural is investing in economy. A player with barely any workers and multiple production structures is all-in or close to it. When the worker count doesn’t match the number of bases, something unusual is happening.

Mid-game scouting

The first scout tells you what’s happening in the first four minutes. But the game doesn’t stop there. Mid-game scouting (6:00-10:00) is about tracking transitions. Your opponent opened Robo and made Immortals, but are they switching to Colossus? Templar? Double Stargate? You need to keep checking.

Terran uses Scanner Sweep for mid-game scouting. Each scan costs you a MULE (about 225 minerals of lost income), so it’s not free. But the information is worth it. Scan their main to see tech buildings. Scan their third to see if it’s saturated. Scan the army when it’s moving out to see the composition before the fight happens. Experienced Terran players also use Sensor Towers, which give a minimap ping for enemy units in a large radius. They don’t tell you what’s coming, but they tell you something is coming, which is often enough.

Protoss has the Observer, a permanently cloaked flying detector. Park one outside their natural to see army movements. Send another into their main to track tech switches. Observers are fragile and Scans or Overseers can catch them, so don’t let them sit still for too long. Move them periodically. The Hallucinated Phoenix from earlier works for mid-game scouting too. It’s cheap and disposable.

Zerg has Overseers (which are fast and make Changelings), plus the natural advantage of creep vision. Your creep spread doubles as scouting. If you have creep across the center of the map, you see every army movement. Zerglings are also great for mid-game scouting because they’re fast and expendable. Park a Zergling at each Xel’Naga Watchtower and outside their natural. If it dies, make another. The 25 minerals is nothing compared to the information.

Reading what your opponent tells you

Some scouting information is indirect. Your opponent doesn’t have to show you their tech path for you to figure it out. You can read the signs.

If a Terran walls off their natural with Bunkers and Siege Tanks, they’re playing defensive. That usually means they’re investing in economy or teching. If they leave their front open and have extra Barracks, expect aggression. A Protoss with a fast Forge usually means Photon Cannon defense at the natural, which signals a greedy build with late units. A Zerg with early speed and no natural Hatchery is about to ling-flood you.

Unit composition itself is scouting information. If you fight a small skirmish at the map center and you see Marauders but no Marines, that’s unusual. The Terran probably has a specific plan (like an early Marauder/Medivac push) and you should prepare accordingly. If you see Phoenixes from Protoss, that means no Oracles, which means your mineral lines are safer, but your Overlords (if you’re Zerg) are in danger. Every unit your opponent shows you is a piece of the puzzle.

The scouting checklist

Here’s what I check at each stage of the game. It’s not exhaustive, but it covers the things that actually change your decisions.

Common scouting mistakes

Not scouting at all. Sounds obvious, but an enormous number of players below Diamond just skip scouting entirely. They follow a build order and hope for the best. Build orders are for the first few minutes. After that, you need to adapt based on what you’re seeing. A build order that ignores scouting info is a build order that loses to anything unexpected.

Scouting but not reacting. This one is more subtle. You send your Reaper into their base, you see a Dark Shrine, and then you... keep building Medivacs instead of getting detection. I’ve done this myself. You’re so focused on your own build that the scouting info doesn’t register. Try calling it out loud when you scout something. Say “Dark Shrine, I need a Missile Turret or an Engineering Bay right now.” It sounds silly, but verbalizing forces your brain to process what you saw.

Sacrificing expensive units to scout. Losing a Stalker to scout a Terran wall is not worth it. Use Hallucination, use an Adept shade, use a Changeling. Cheap or free scouting exists for every race. The exception is if you see something suspicious and you need confirmation immediately. Losing an Overlord to confirm a Banshee rush is worth it. Losing an Overlord just to see a standard build is not.

Scouting only once. The game changes. What they were doing at 3:00 is not necessarily what they’re doing at 7:00. A Protoss who opened Stargate might switch to Templar tech. A Terran who played bio might add Factories for mech. You need to keep checking. Set mental reminders: every time you inject as Zerg, glance at the minimap. Every time you drop a MULE, scan if you haven’t in a while.

Using replays to learn what you missed

Here’s the real power of replay analysis for scouting: you get to see everything your opponent did, including the stuff you didn’t scout. Every replay has the full game state for both players. You can see exactly when they started their Dark Shrine, exactly when they moved out, exactly when they took their third.

Now compare that to what you saw during the game. Did you scout at the right time? If their Dark Shrine started at 3:45 and your first Observer wasn’t out until 5:00, that’s a 75-second window where DTs could kill you. Could you have scouted earlier? Was there a sign you missed? Maybe they had two gases before their natural and you saw it but didn’t recognize what it meant.

The replay analysis will show you the timeline of both players’ builds side by side. Look at every moment you were surprised in the game. Then look at the replay and find the moment where, if you had scouted, you would have seen it coming. Over time, you start recognizing the patterns. Two early gases? Better get detection. No natural at 2:30? Something aggressive is happening. No third at 5:00? They’re about to hit you with everything. These patterns become automatic once you’ve seen them enough times in your replays.

The goal isn’t to memorize every possible build your opponent can do. It’s to recognize the categories. Is this aggressive or economic? Is this standard or unusual? If it’s aggressive, make units. If it’s economic, match it or punish it. If it’s unusual, scout more before committing to a response. Build your army composition around what you see, not what you hope.