Fear the Reaper, Man! Scouting in TvZ

Use your Reaper to read and react to common Zerg openers!


Starcraft is an incredibly complex game, and many of its details that are essential to the pro scene are, at best, vague concepts to newer players. One of the most important such elements of competitive Starcraft is scouting for information. Since the game map is by default shrouded in the “fog of war,” every serious player will dedicate units to investigating the opponent’s early decisions. But what should you actually be looking for? And what do you do in response? This guide will examine the Terran vs. Zerg matchup, as well as give players of all levels an idea of what your aim with early Reaper scouting should be.

The standard Terran opening build is the Reaper Expand. This build gets out a quick natural expansion with a single Reaper for early-game scouting, harassment, and defence. If used correctly, a Reaper can hold any early push a Zerg player might commit to, while also punishing greedy builds. How do we accomplish all that with only a single unit? It comes down to knowing what to look for, and when to look for it!

Zerg have a few different viable openers, but the three most common are Hatch First, Pool First, or Gasless Third.

Hatch First

  1. Start second Hatchery
  2. Vespene Gas Extractor
  3. Spawning Pool

Hatch First is the most common opener and offers a middle ground between economic expansion and early defence. A Zerg player going Hatch First is looking to develop a strong economy while remaining safe against potential Terran all-ins. This is a difficult opener to exploit, since it ensures a reliable early Zergling speed.

Pool First

  1. Spawning Pool
  2. Vespene Gas Extractor
  3. Start second Hatchery

Pool First commits the Zerg player to early aggression as their economy will be relatively weak. Pool First will generally send out early Zerglings to harass the SCV building your low-ground Command Center, and maybe even force a cancel!

Gasless Third

  1. Start second Hatchery
  2. Spawning Pool
  3. Start third Hatchery
  4. Vespene Gas Extractor

Gasless Third is the least aggressive of these three opening builds, although it can quickly transition into a number of dangerous all-ins! These Zerg players aim to quickly take three bases to gain a substantial economic advantage. This delays the Zergling speed upgrade, leaving the opponent weak to early pressure!

The key to scouting successfully is knowing what information you need to glean from your opponent! When our first Reaper spawns, we send it immediately to our opponent’s natural base. We’re looking for their second Hatchery around the 2:30 mark, and will almost certainly see one of three different things.

#1: No Hatchery whatsoever

If you don’t see a natural expansion Hatchery, Zerg is using either a Pool First or Hatch First build and may be one-basing you! This is a dangerous situation, as Zerg could be preparing an all-in, or just expanding in an unconventional location. You must scout the third to check if they took that base before the natural. If they didn’t, evacuate to one base and get your defenses up ASAP! If you forget to check the third, then it is easy to incorrectly assume they are doing a single-base all-in and stifle your economic development in response!

In the following image, the opposing Zerg used a Pool First build but attempted to throw me off by hiding his second Hatchery at his third expansion. If I hadn’t scouted the third base, I may have gotten worried about an early all-in and built too defensively to keep up in economy!

Pool First, 3rd Expansion

#2: A Hatchery almost done building, or one that has just been completed

A just-complete or near-complete Hatchery indicates the opponent went for Pool First, which means that he is looking to do early damage. Most Zerg will send out 2 – 8 Zerglings to either kill the SCV building your next Command Center or the Center itself, depending on how heavily they commit. In this case, you should instantly pull the Reaper back to your base to help defend against the incoming Zerglings. If he sends more than four Zerglings, you may need a handful of SCVs to decisively fend off the Zerg. As long as you can hold, you should have an economic advantage going into the midgame!

In the following image, the Hatchery has just finished and has a single Drone mining. This indicates that the Zerg player spent a significant amount of money elsewhere – which must be a Spawning Pool, given the current game time.

Pool First, Natural Expansion

#3: A finished Hatchery with creep that is almost done spreading

This is the most common thing you will see. The only way to finish a second Hatchery this fast is by building it before Spawning Pool, which accordingly means that it’s impossible for any Zerglings to be on the way to our base. If we see a quick Hatchery, we need to ascertain one more thing: whether this is a Gasless Third or a standard Hatch First build. To determine this, we send the Reaper to his third base, to see if he has taken it or not. If we do not see a third Hatchery then the Zerg player went standard Hatch First with Gas behind it. If you dosee a third Hatchery, it indicates that the opponent delayed taking Gas in order to maximize mineral output. In this situation, you will have the early-game map control and can consider being aggressive!

In the following image, our Reaper scouts that the opponent has already taken started a third Hatchery and has a well-stocked second Hatchery at around the 2:30 mark, which means that he went Gasless Third.

Hatch First, Gasless Third

If your opponent plays greedy by taking this very early third base, you have two options to punish it. We can attack the morphing Hatchery with the Reaper to weaken it for a later push, or we can go into the Zerg expansion and try to get Drone kills. If you do not see a third base, send the Reaper back to stand just outside his natural as in this image:

Reaper Positioning

There are two reasons that this is essential: the first is to kill any Drone trying to start a third Hatchery. This effectively means that Zerg will not be able to take a third base until Zergling speed is complete, which is usually around the 3:30 mark. Just by having the Reaper in position, we can delay the Zerg third base for a full minute! Smart Zerg players will try to distract your Reaper so they can sneak a Drone out to take their third base, but do not be fooled – make sure that the Zerg player can’t take his third base until he has Adrenal Glands!

The second reason to position the Reaper outside the opponent’s natural base is in case he suddenly transitions into aggression and sends out a big wave of Zerglings. If he does, the only way to avoid crippling damage is to complete our natural wall and build a Bunker behind it ASAP. At around the 3:30 mark, most Zerg will reliably have their speed upgrade finished. This means that they will be able to hunt down your Reaper and take a third base uncontested. The only time that competent Zerg players will not do this is if they are planning a two-base strategy.

So if a Zerg player is not trying to take their third by around 3:30 – 3:50, they are doing something else. In this situation we must find out what this “something else” is, so that we can prepare for it! Send your Reaper to scout the Zerg main base to see whether they are upgrading to a Lair. If you see a Lair upgrade in progress, the opponent is most likely doing a two-base Mutalisk build or a Nydus Worm all-in. If they are not upgrading to Lair, they are probably planning a Roach-Ravager all-in or a Baneling Bust.

There are endless possibilities in this incredible game, and infinite variations in how the situation can develop from what I’ve outlined here. It also is important to mention that these timings are most applicable to opponents with a strong game sense and plan: in lower leagues, it’s better to be safe than sorry! The reason pros skip Bunkers is that they need to cut every possible corner! This is not necessary unless you’re playing in the GSL, and as a result we can afford to take extra defensive measures. It is impossible to overstate the importance of effective scouting. If you understand your opponent’s game plan, you’ll also be able to effectively counter it!

With all of this information, you should be able to scout and prepare for everything a Zerg can throw at you in the first few minutes! See ya on the ladder!