Although mech was expected to be the main composition of Terran for Heart of the Swarm, most players opted for the standard Marine Tank composition when the expansion was just released. The new Medivac speed boost ability was often cited as the reason for the choice. However, Medivac had been heavily used in mech recently.

I will cite Maru’s adoption of mech against Soulkey in WCS Korea Ro32 as the pioneer of this concept in the progaming scene. While the community was busy arguing whether mech is viable in TvZ, and how Soulkey didn’t deal with it well enough, it was the opening that impressed me. Maru opened up with Hellion and Helbat drops, and transited into mech. This was quite effective and innovative at the same time for several reasons. First, it has good harassment ability which pins the opponent in his/her base. This is important if you want to go into mech. A good player will not allow you to just sit back and macro up to get a good mech composition. Mech has to be proactive in its own way in order to buy time to reach a big enough army to push across the map. This was evident in Wings of Liberty whereby Terran often opened with either blue flame Hellions or Hellion and Banshee for mech composition. Second, constant Helbat production doesn’t conflict with mech composition. Third, it is more effective in killing workers than Banshee and Hellion.

If there is only one match up that mech is viable, it has to be TvT. The KeSPA Terrans seem to be more open to the adoption of mech than eSF Terrans. Flash chose mech against INnoVation in WCS Korea Ro16 group of death, and used the same strategy in all three games (I bet he planned to use the same strategy in the second game which he was killed off by the early Reapers). Interestingly, he picked Whirlwind in the third game after INnoVation picked unorthodox builds in the two previous games. I tweeted the following while I was watching it live.

I thought his mind set was “he tried to cheese me in the last two games. I’m going to choose a big map and win him in a standard Marine Tank game. I have already defeated him on Whirlwind in MLG.” Whirwind is the last map in the map pool that you want to use mech. I admit that I was surprised when Flash sticked to mech in whirlwind.

The main reason that big maps are relatively less suitable for mech is its mobility. Flash’s answer was Medivac. When INnoVation loaded up his bio from Flash’s third and dropped in Flash’s main, Flash followed those Medivacs with his own Medivacs which were loaded with Helbats. It was an extremely effective way to deal with the mobility of bio, especially with those missile turrets. Furthermore, Helbat drop is more effective than cloaked Banshee in the mid game and late game. You can just drop the Helbat at the mineral line to trade with the opponent, but it is harder to be cost effective with Banshee when there are turrets.

However, Helbat drop comes with an opportunity cost. The Starport, with reactor, is used to produce Medivacs instead of Vikings. Without Vikings, mech doesn’t have anything that can hit air. Thor is not particularly good against bio. Bio can actually do  a quick tech switch and take advantage of that. I had written about how Thorzain got an early Battlecruiser against mech in the first post of this blog.

Medivac mix in mech is really innovative and can possibly revolutionalize the match up. But it still requires further experiment and polishing. In a more recent game, Ryung mixed in a few Vikings into this new style of mech against Supernova, who got a few Battlecruiser to deal with mech as I’ve mentioned earlier. It is just a matter of time that players figure out the new mech style.