TvZ: Evolving Mech Style in 4.7.1

Mech is evolving after patch 4.7.1 kicked in. I want to discuss some of the interesting innovations with the current mech style.


For a long time (even before Legacy of the Void), Blizzard have made it clear in their design and balance discussions they want to make mech viable. I previously mentioned that Blizzard’s untimely patches is one of the reasons why mech did not really get a chance to establish itself. Whenever mech seems to become mainstream, Blizzard’s patches go live to reshuffle the metagame.

There are some negative unintended consequences from the “mech it work” initiatives. The pre-4.7.1 Cyclone was designed to specifically allow players to use Cyclone and Hellion together in the early stage. While it did work as intended in a way, it had negative spill over effects on TvT and TvP. More broadly, the desire to ensure mech is viable in fact results in a net nerf to Terran.

Surprisingly, Blizzard remained silent about mech in their original discussion for patch 4.7.1. It appears that there is no potentially good change that may make mech more popular without upsetting the overall balance. Ironically, it is when Blizzard did not explicitly “mech it work” that we see mech blossom. In this article, I want to discuss how the once niche battle mech, which emphasises on being the aggressor, rises in patch 4.7.1.

Mech was traditionally considered a defensive composition that sits back to produce a cost effective death ball army. Clinging onto the conventional knowledge from the Brood War days, Artosis defines mech as a playstyle, a defensive one specifically. This definition implies that, mech cannot be played aggressively or proactively, or else that is not considered mech. While this definition captures the two familiar types of mech playstyles [1. defend and move out with 2-2 max army; 2. defend and slowly consume the map (see vod below for an example)], it does not adequately consider other plausible ways to play a certain composition. With this limitation in mind, my definition focuses on the investment on the types of production and upgrade, and I had discussed this in this article three years ago. The current battle mech diverges from the old school defensive style.

Basics of battle mech

Cyclone and Hellion make up the core of this composition. The common strength of these two units is their mobility, and this unique attribute defines its proactive playstyle. This style is not new, as INnoVation once popularised it in the match up using the old Cyclone. Unlike the old Cyclone, the current Cyclone relies on the Lock On ability rather than brute force. Hence, despite having the same core units, the old and new battle mech adopt different styles.

The sheer number of Cyclone for the old style poses a big threat. Given that Cyclone’s value does not scale well, an attack with Cyclone is inevitable. Terran can hit a timing with Cyclone and Hellbat, and it is potentially deadly if Zerg do not prepare well enough. Thus, Zerg are required to make units to battle Terran head on. See vod below.

In contrast, the current style does not “get in your face”, but it uses a hit and run style to gain value from Cyclone’s Lock On. It is more of poke and pick off units, then move back for the ability to cool down. Hellion complement the Cyclone well, because Cyclone is very bad against Zergling. Uthermal should be credited for this, as he was the first notable player to use this when 4.7.1 went live, to the best of my knowledge. He used this style against Zerg at Home Story Cup (HSC). The vod below shows an initial attempt to use battle mech right after 4.7.1 was live. This is a good example of how one should not engage in a frontal battle with the current battle mech.

This may appear as a specific bad example, but by no mean Uthermal is bad at using the new battle mech. In fact, his approach to mix in Banshee and Battlecruiser are adopted by other top Terran players. The complexity of the composition makes it difficult for Zerg to identify and execute a good counter. Below vod shows how Cyclone should be used in an engagement.

The other worth noting difference between the old and current battle mech is the operational time frame. As mentioned earlier, the old Cyclone has an early effective time frame, but its effectiveness drops as the game progresses. The current Cyclone, however, is used as a mid game unit in the battle mech composition. This is best illustrated by comparing the build orders.

Both usually use an expand opening (e.g., Reaper expand) into Reactor Hellion. The old one produces a pair of Cyclone after the first pair of Hellion, and the build subsequently keeps producing Cyclone with Reactor Factory whenever the resource allows. In contrast, the current one goes with a conventional 1-1-1 with Reactor Hellion and Starport. The Starport produces either Banshee or Battlecruiser, which I would discuss later. The production of Cyclone does not start until the third Command Centre and two more Factories are added with Tech Lab. See figure below for a comparison.

I want to focus my discussion on three unique aspects of the current battle mech:

  1. Mix in Banshee.
  2. Mix in Battlecruiser.
  3. Do not transition to Siege Tank.


Banshee is an important addition to the current battle mech. The Hyperflight Rotors upgrade makes it one of the fastest units in the game, so Banshee fits the high mobility feature of the composition. Banshee provides crucial utilities at different stages of the game.

First, in the early game, Banshee and Hellion are considered the most well rounded composition in TvZ since Wings of Liberty. Hellion is good against Zerglings (and Banelings), and Banshee is the perfect counter against Roaches in the early game. That means the current battle mech adopts the most refined early game build.

Second, Banshee, as an air unit, provides vision that allows Cyclone to Lock On to the intended targets.

Third, Banshee fills the gap that the current Cyclone does not have the “bite” of the old Cyclone. While the current Cyclone is effective in “hit and run”, it could be problematic when Zerg force an engagement with a sizable army. Banshee provides the needed damage in the mobile engagement.

Fourth, Banshee can create space for the ground army. A group of Banshee with Hyperflight Rotors is like a flock of Mutalisk when it is used to circle from one base to another to find damage. It is difficult for Zerg to “catch” them, because Corruptor is not quick enough and Hydralisk cannot fly. Hence, Zerg are forced to move their Queen and Hydralisk to deal with the Banshee. This opens up opportunities for Cyclone and Hellion to get work done elsewhere. The vods below are some examples.


Contrary to conventional assumptions, Battlecruiser is now used in the early to mid game transition for battle mech. Battlecruiser is an alternative to Banshee in that early time frame. You use the same build, then you put down a Fusion Core instead of making a Banshee immediately. The first time I saw this was when Uthermal used it against Serral in HSC (see vod below).

I had a negative impression of how Battlecruiser was used in the vod above. A Battlecruiser itself costs as much as a Command Centre plus 300 gas, so it is extremely important that you gain value from it asap. If you intend to use it later, then it is always better to spend the resource on a Command Centre first. Uthermal moved his first Battlecruiser around rather aimlessly, so that was definitely not the best way to get value out of it. Korean Terran players recently adopted the build and improved the execution by using the Tactical Jump immediately into Zerg’s base commence attack. See vods below for examples.

At that time around 5:30, Zerg have to rely on Queen and Spore Crawler to defend against Battlecruiser. Simplying moving the new Battlecruiser (which can attack while moving) near the mineral line is annoying for Zerg. Execution wise, it is not a good idea to trade Battlecruiser’s  health point against a group of four to six Queens. You want to attract the Queens to the Battlecruiser and run the Hellions to the mineral line to kill Drones. The first Battlecruiser should maintain a healthy health point to attack again when the second Battlecruiser arrives.

As I was researching on this topic, Laura told me in a private chat that it is hard to gain value from killing expensive Zerg units, because Zerg simply have Zerglings and Queens. It is difficult to justify Terran’s investment on a Battlecruiser at that early stage of the game (400/300 for the BC, 150/150 for a Fusion Core, and 150/150 for Yamato Cannon research). She pointed out that the indirect damage comes from delaying Zerg’s fourth base.

While I could not pin point the specific merits of Battlecruiser myself, there appears to have indirect evidence to her arguments. Some players who opt for the early Battlecruiser build do not continue to produce it in the mid game, and they instead switch to Banshee (e.g., in the game between TY and Rogue above). This implies they perceive Battlecruiser has a very short effective time frame, and the goal is to extract as much value out of it during that period. This is consistent with Laura’s argument, which suggests the benefits are related to the time frame when Zerg get their fourth. To reinforce her arguments, she mentioned that INnoVation’s Battlecruiser always retreats to the fourth base location, and a constructing Hatchery without armor cannot withstand a Battlecruiser’s damage. Thus, it appears that the benefits come from the ability to “contain” Zerg.

With that being said, Battlecruiser is also massed in the mid to late game. Hence, Battlecruiser is also a transition option later in the game.


Uthermal did not transition out of Cyclone and Hellion in his games, and this signals that a Siege Tank transition may not be necessary. Consistent with the notion that the old Cyclone does not scale well, the old style transitions to a more typical mech composition with a focus on Siege Tank. The current Cyclone is in fact the main mid game unit that sort of replaces Siege Tank. Recently, however, newer games showed that Terran players tend to mix in some Siege Tanks. See vods below for examples.

The current Cyclone breathes new life into mech. Although Siege Tank is the heart and soul of mech, Zerg have tailored counters in the mid game using Swarm Host. Zerg’s improved understanding of mech has directly led Terran to mainly use bio in the match up. As such, while Siege Tank still has a place in mech, it does not appear to be a staple in the modern mech composition. More importantly, Terran players are experimenting different transition in the late game. One is rather intuitive, which is the Battlecruiser. This is usually an option when players have invested in Battlecruiser early in the game as discussed just now. The vod below is an example. You can tell that the effectiveness of Corrupter and Viper against Battlecruiser is not as great as one would assume. Both Corrupter and Battlecruiser have an attack range of 6. So, Terran can right click the Battlecruisers to retreat, and let them deal damage to the Corrupters automatically when the Corrupters are chasing them. Battlecruiser would do better than Corrupter in this “moving” engagement because of their ability to move and attack. Viper’s abduct can be countered by Battlecruiser’s Tactical Jump, so it does not appear to be a good solution. Several people have mentioned that Infestor may in fact is the answer.

The other transition choices are more of the typical late game TvZ units that we are familiar with, namely Ghost and Liberator. The two vods below showcase how Ghost and Liberator can be included respectively.

Ending words

This new mech is an unexpected composition. Despite its prominence in the metagame now, this new mech style is still at its infant stage. I doubt there is much room for improvement in the early stage, but it appears that top Terran players have not figured out the optimal composition and transition in the mid and late game. Similarly, Zerg are also learning how to deal with this new mech style.

I thought of discussing the build orders and Zerg’s reaction in this post, but I will probably leave that for future posts. This article already contains more than 2000 words.

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