15 gas opening is the most common build for TvP in recent IEM – World Championship and MLG Winter Championship. The build is not exactly new as it has been used in Wings of Liberty for TvT, albeit it wasn’t as popular as other builds.

The build has been mentioned in Team Liquid and Reddit, but I feel that the “descriptions” do not clearly identify the true value of the build. This post is about how the build could shape up to adapt to various options of Protoss.

Basic build order

10 – Supply depot

12 – Barrack

14 – Supply depot (Use the scv that is building the barrack to build it, then order it to continue building the barrack. This is to block off scout as 2 supply depot and 1 barrack can wall off the ramp.)

15 – Refinery

16/17 – Orbital command

Get a scv to finish to unfinished supply depot. Get a scv to scout.

Build 2 Marines, then build a reactor on barrack.

@400 mineral – Command centre (Orbital command @ 100%)

The scv should scout if opponent has gone for one or two gas by this time. If two gas have been taken, the command centre could be built on high ground (preference). Scout for proxy (Stargate) if you see 2 gas.

@100 gas – Factory

Build a bunker if the command centre is built at low ground.

Continuous production of Marines when reactor is done.

@100% Factory – Starport

Produce two Widow Mine.

@100% Starport – Medivac

@100% Starport – Second refinery (Timing varies slightly)

Reaction

Try to scout if opponent has thrown down a Nexus if you didn’t see it just now (especially if you see 2 gas).

It is optional to scan Protoss’s main if you cannot confirm if s/he has a Nexus. React accordingly to what you see from the scan.

Stargate (Oracle animation)

– Plant a Widow Mine at each Mineral Line. It can one shot an Oracle.

– Build Vikings (Optional. No more than two unless you think opponent is going to all in with more than 4 Oracles.)

Twilight Council (likely is Blink)

– Plant a Widow Mine at the entrance of the natural. Plant the other where you think opponent can blink into the main, but make sure it’s not too close to the edge. This is because there will be an Observer for the blink stalker to blink in. You do not want the Widow Mine to get picked off before they blink in. You can build a bunker in the main to anticipate the blink in.

– Build a tech lab on the Factory. Since siege mode no longer requires research, it is very effective against blink stalker at this stage (Refer to Innovation vs MC on Cloud Kingdom). Position the tanks accordingly.

Nexus

– Apply pressure since you took the early gas compared to 1 rax expand build.

– Choice 1: Drop with two Widow Mine and four Marines

– Choice 2: Attack the natural with two Widow Mine, Medivac and eight Marines

– Choice 3: Drop two Widow Mine. Walk around with Marines to clear tower. Using Marines to walk to opponent’s natural is optional.

Further build order

It is important to note that you need to get to the convergent point of three barracks with add-on.

– Build 2 barracks

With one rax expand, 1 tech lab + 2 reactor or 2 tech lab + 1 reactor are both up to personal preference. However, since this build focuses on spending resource to tech up and not spending the gas on upgrade first, the add-on should be 2 tech lab and 1 reactor for 15 gas opening. Based on the VODs I have watched, the pro players diverge more than expected in terms of how to get to this convergent point. Personally, I prefer the following.

– Build two tech lab on both factory and starport respectively. (The 2 barracks are still building)

– Third refinery and Engineering bay (@100% – +1 upgrade).

@100% tech lab – Lift up both starport and factory

– Land the two barracks on the two tech labs and research stim and combat shield.

– Build 1 Medivac

Now there are two Medivac, you can use them to harass.

– Reactor on factory

@100% Medivac – Swap Starport on the reactor built by factory

It then shapes up to a standard game. Thus, you can build two more barracks or get a third command centre from there.

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In sum, 15 gas build allows you to tech up quicker than a rax expand by delaying the command centre.

Many have been scrutinizing the pressure aspect of this build with Medivac and Widow Mine, but the true value of this build is that it can react to almost every build that Protoss does in the current metagame. Widow Mine can be used offensively and defensively based on the scouting information. Widow Mine is the best defense against Oracle in early game. Indeed, Oracle vs. Widow Mine is the current TvP metagame in early-mid game. The next post is about Oracle mind game in the current metagame.