There are good harassments which deal so much damage that they pull the opponent apart, and there are also bad harassments which simply donate units. The effectiveness of a harassment hinges on how well the player stretches the opponent’s attention, and how little attention the player needs to execute it. I want to discuss about how the consideration of attention can improve harassment execution.

Basics of harassment

As expected, Liquipedia describes harassment well. The key is “cause damage to the enemy without a large engagement”, so doing a big drop in opponent’s main should not really be considered a harassment.

… the act of using a small number of units, usually with superior mobility, to cause damage to the enemy without a large engagement.

Most know what harassment works in general, but the effectiveness of harassment often seems “random” to many players. It works wonderfully as the opponent is caught off guard at times, while sometimes opponent just appears as if to be on top of his or her game and prepares well for it. However, when you apply rationale of players’ capability to only look at one thing at a time, the effectiveness of harassment is much more accountable than one thinks.

The key is to harass a location where opponent is not paying attention. Intuitively, while you are executing a harassment, you should do another thing that attracts opponent’s attention. For instance, you can threaten to attack the third from the front, while you have a drop in opponent’s main. In line with this rationale, the more places you put pressure on, the less likely it is for opponent to defend the harassment well.

However, while it is true that the more places you hit the harder it is for the opponent to defend the different locations, it is also harder for you to execute the harassments well yourself. In other words, it becomes a battle of who can multi-task better. In general, the offender has a priority advantage, because you know where you have allocated most of your forces. Thus, the offender is more likely to make better decisions in where to spend his or her attention on. On the other hand, the defender can also have an advantage in multi-tasking by using static defence to deal with harassment, and this requires little to no attention. When you put these points together, effective harassments should follow these few points.

1. Maximise opponent’s attention load by
   • forcing him or her to place attention on as many location as possible, and
   • making it difficult to decide where to place his or her attention on.
2. Minimise your attention load by
   • picking harassment options that have low attention requirement but high damage output, and
   • plan where to focus your attention on before the harassment and other engagements occur.

Executing harassments

Let’s start with the basic, which is to attack on multiple fronts as shown in the vod below. I will use TY’s vods for explanation in the rest of this post, because he executes his harassments based on the above pointers better than most players. Moreover, time after time he has shown that he is a tactical master, who knows when and where to hit.

When TY loaded up his Medivacs and attempted to drop in the main, he had another group of units moving towards the top base of the Protoss player. Although he later reacted according to the situation and decided not to drop, the core of the idea is to intentionally set up threats on multiple locations. Most players understand and do this well in game. What I am going to show next is what most players don’t do that well.

The above vod shows how TY always has the game plan to stretch opponent’s attention. I put a timestamp at the place when TY had a Medivac of Marines at the north, and his main army in the middle, Subsequently, he sent a Liberator to the south, and harass the mineral line after the Medivac was destroyed. TY was basically hitting at more than one location at the same time throughout the whole mid game. Later, at 11:00 in game time when there was a big battle that both players must focus on, TY had a Liberator sieged up at one of the mineral lines. After that Liberator was taken out, he sent other Liberators to siege up at different mineral lines. While these Liberators was stretching opponent’s attention, TY made his move to attack  Zerg’s newest Hatchery. The main purpose of these Liberators was to force Zerg to deal with them, while TY could focus his attention on other locations that the Zerg did not have the luxury to.

When you analyse it from the attention perspective, a Liberator is the perfect tool for harassment. It requires opponent to send specific units to deal with it since it’s an air unit, and Zerg cannot simply A-move a few Queens over as the Liberator usually trade well against Queens that aren’t micro-managed. It also requires minimum attention from the Terran player perspective as you can find a spot to siege up and just leaves it there to get picked off eventually while you focus on other places.

In fact, TY’s choice to use Liberator as a harassment tool in mid and late game is a revolution move, because Terran have been using Medivac with Marines (occasionally mix in a Widow Mine) for this job (MMA is famous for it). Unlike the Liberator, a Medivac with Marines requires more attention from the Terran player as you need to pick up the units when the Zerglings are there, and move away and come back to unload it again later. Further, a Liberator (150 mineral and 150 gas) is cheaper than a Medivac with eight Marines (500 mineral and 100 gas). Therefore, Liberator is a more attention and cost efficient harassment option than Medivac with Marines.

The Liberator harassment can also be used against Protoss. The vod above shows how TY had Liberators at Protoss’ mineral lines while he was having a big engagement. The Protoss player should also be given some credit for making the best reaction possible by sending a Phoenix to each of the sieged mineral lines to deal with the Liberators, while he pulled the Probes away. The lost mining time could be considered indirect damage.

The vod above further highlights TY’s consistency in his game plan to stretch opponent’s attention. One thing I like TY’s multi-task harassment playstyle is that he does not multi-task in such a way he cannot handle himself, and this is consistent with the offender advantage I mentioned.

Another important aspect of TY’s approach is the timing of the harassment. The vod below shows that TY did not siege up his Liberator at opponent’s mineral lines, unless he was pressuring at another location to force the opponent to place attention on multiple places. He flew two Liberators to the air space behind opponent’s bases and chill, while he moved his bio to attack another location at the top. He only sieged up these Liberators at the mineral line after he scanned, and this harassment effectively interrupted mining. It was extremely difficult for opponent to clear these Liberators because both players had to focus on the main engagement elsewhere. Not surprisingly, the Protoss player sent a few A-move commanded Stalkers to clear the Liberators while he focused his attention elsewhere, and those Stalkers simply got destroyed by the Liberators. This game shows how TY utilises those pointers I stated above in his harassment execution.

Unlike TvP and TvZ, TvT is a match up that Liberator is not in the main army composition unless it is in a late game air versus air situation, and hence, it is less convenient to send Liberators to mineral lines at suitable timings. TY came up with a very interesting and effective approach to harass the opponent based on the attention rationale.

The two vods above show how TY executes Marine drops differently from almost every other Terran player. Most players either drop the Marines directly at the mineral line or at the edge before running in, and both are attacking at one specific location. In contrast, TY unloads a few Marines at one mineral line, and then his Medivac will unload the rest in another mineral line. The Marines basically do not require attention after they are dropped (just Stim and A-move), and they will automatically kill Scvs. The job is done when opponent also sends some units to deal with these Marines, after they have killed some Scvs and delay mining time. Again, all these are consistent with the attention pointers I stated.

Ending words

There are other things to consider in harassment, like deducing where your opponent’s units aren’t located or force them to move elsewhere, but I want to focus only on the attention aspects of harassment in this post.

The fundamental logic behind this attention based harassment execution is not limited to Terran. Warp Prism late game Zealot dump is in my opinion one of the best harassment tool, because it takes little attention from the user. However, the defender is required to send a big chunk of his or her army to deal with these +3/+3 tanky Zealots. Let’s use Terran as an example, you must send bio units with Medivac that takes up more supply than these Zealots in order to clear the Zealots (usually around 1.5 times), and the fewer units you send the more you are required to micro against them. On the other hand, these Zealots basically require little to no micro to be effective for their purpose, and the Protoss player can advance the main army to attack a Terran base. Protoss can mix in a Dark Templar to complicate things and stretch the attention of the defender further. This actually happened a lot in Heart of the Swarm.

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