12/12 Reaper opening is the most common build in TvP now. Despite its many merits, Reaper opening is very vulnerable to proxy Oracle due to the low Marine count when the first Oracle arrives. Even a top pro Terran player like INnoVation has looked helpless in such situation. This post suggests a counter intuitive way to solve this problem.

Background

Reaper opening allows you to scout and harass Protoss at the beginning. Its main merit is its ability to scout Protoss’ build even if there is a Stalker. It is a macro build that allows you to expand and shape up to a standard macro game. The general build order is 12 Refinery and 12 Barrack.

There are various variations of 12/12 Reaper opening.

Sometimes a scouting Scv is sent at 15 supply to block opponent’s natural with an engineering bay. This is seen as optional. The purpose is to delay opponent’s expansion. It could be effective if opponent does not get a Zealot and wants to expand slightly earlier. Do not complete building the engineering bay and cancel it at the last second to delay opponent’s expansion as much as possible.

Problem

No matter which build order you go for, you will produce the first pair of Marines after the barrack has gone through a round of Reaper production (one without reactor or two with a reactor) and the build time of a reactor. The first pair of Marines will start training at around 4:25 and complete by 4:50. A proxy Stargate Oracle will be done by 5:00 and reach your base by 5:10 – 5:15. Thus, when the first Oracle reaches your base, you have only two Marines to deal with it, and damage is inevitable. This situation happened in Season 1 WCS Final game 2 on Bel’Shir Vestige between INnoVation and sOs.

INnoVation scouted his opening’s base with the Reaper and noticed that the number of pylons and Assimilators indicated a proxy stargate opening. He immediately moved his Reaper to the common proxy location and found the stargate. He then reacted by building a bunker at the mineral line. The Oracle arrived before the bunker finishes and killed the Marines. The Scvs started to picked off and the bunker could hardly complete. Even if it did get completed, there were no Marines.

What if he waited for the second pair of Marines before he engaged the Oracle? It does not help. A full health Oracle can kill five Marines in a face to face battle without dying. So by waiting for the next pair of Marines ( four in total) which should appear by 5:15 does not make a difference. The game could have ended when the second Oracle arrives in the base by 6:00. Terran just look helpless.

Progamers’ reaction

Based on the example above, there is really nothing much you can do even if you scouted it as early as INnoVation did.

In a game in proleague, Flash scouted Dear’s proxy stargate even earlier than INnoVation scouted sOs’. Flash tried to target the pylon down with the Reaper and Marines. However, that still cannot prevent the first Oracle from appearing.

In this game, Dear built the proxy in a weird location which got scouted really early. The situation would have worked out even better if the proxy location is more normal and not get scouted that early.

Let say you scout the typical proxy location once your Reaper appears and find the proxy stargate. You start to attack the pylon with your Reaper. Assuming Protoss does not react, the Oracle may or not may finish in time depending on the location. It will be really close. However, Protoss can just build a second pylon right away with the Probe still idling next to the stargate and there is no way the Reaper can stop the Oracle from appearing. You cannot send Marines to target the pylon as they won’t make it in time. Protoss can also send a Stalker to the stargate to chase the Reaper off, if the probe is not there. I have seen quite a number of progamers react by building a bunker next to the stargate immediately, but none has made it work. In my opinion, it is a panic move which does nothing.

How about building a turret? Sure, there is a +1 upgrade Reaper opening variation with an early engineering bay, which both Flash and Bbyong had used it in WCS Korea. In the Flash vs. Dear game, Flash did start an early engineering bay but the turret cannot finish in time . Even when the turret does get completed, the damage is done.

Proposed solution

The proposed solution is to build an engineering bay and a turret.

What are you talking about? Didn’t you say it doesn’t work?

I am referring the engineering bay that is used to block at opponent’s natural and not the early engineering bay that is part of the build. Usually, you do not finish building the blocking engineering bay and cancel it at the last second when Protoss tries to destroy it and expands. To counter the proxy Oracle, I propose finish building it. This may sound counter intuitive, but I will explain why.

It is important to highlight that it is not a blind counter by finishing the blocking engineering bay. Here is how you do it.

Send a scouting Scv at 15 supply and build an engineering bay at opponent’s natural. The blocking engineering bay starts building at around 3:20. Note that it takes 35 second to complete. Pause building the engineering bay when it reaches around half of its required build time (around 3:40), and use the Scv to scout opponent’s base. Count the number of pylons and assimilators to look for sign of a proxy stargate. If there is only one pylon and two assimilators with three probes each, it is [extremely likely] going to be a proxy stargate. Move the Scv back to the natural and complete the engineering bay if you think it is a proxy stargate. It should complete by 4:30 depending on the time that the Scv took to scout. Then, build a turret in your mineral line, which completes in 25 second. It should finish at around 5:00, which makes you safe from the Oracle (arrives at 5:15). Although you do not get the 94 mineral back from cancelling the engineering bay, the amount of damage reduced in your base is much more significant.

Furthermore, the Reaper appears at 3:30 (assuming it is not reactor then double reaper build). If you move the Reaper to scout the key proxy locations straight away, you should scout the stargate. This can help to confirm if it is indeed a proxy stargate. To make things better, rally your barrack to the turret to prevent the Oracle from picking them off before you have more than five Marines.

Summary

It is possible to not take serious damage from a proxy Oracle build using a 12/12 Reaper opening.

Step 1: Scv scout at 15 (can be 14)

Step 2: Build an engineering bay at opponent’s natural

Step 3: Pause building the engineering bay at around half of its build time and scout opponent’s main base

Step 4: If there are signs that indicate a proxy stargate, complete the engineering bay.

Step 5: Build a turret in main base.