It was once a bird of prey; a “tactical strike craft,” as mentioned in the Starport’s description. Against the Zerg hordes, it once flew overhead to cover its faster brother, the Hellion, in TvZ early to mid game. It sniped Queens and 3rd Hatcheries, exploited lack of spore crawlers by decimating Drone lines, scouted tech paths, and pushed creep back. It even held all-ins, peppering Banelings and Roaches as they moved across the map. And if any of them survived the early phases of the game, they would be useful in the later pushes of Terran, spotting for Tanks and precisely thinning Baneling numbers before they impacted on the Marines.
In Heart of the Swarm, however, Banshees have unfortunately faded from existence due to a number of factors:
a) Reapers were reworked completely. With the introduction of a self heal, speed buff, and removal of the Tech Lab requirement, Reapers became the go to unit to harass and disrupt, as well as provide invaluable scouting information. Best of all, they didn’t even need an expensive upgrade to reach their full potential.
b) The Spore crawler became available from the Spawning Pool. The concept that a few small mineral structures could almost completely nullify a 525 gas investment (Starport, Tech Lab, Two Banshees, and Cloak) was not a pleasant one for Banshee users. This gas very easily could have been +1/+1, StimPack, Combat Shields, and Drilling Claws all put together.
c) Mutalisks were buffed. Because of their increased healing and speed, more and more Zerg players began going for them earlier in higher numbers. Once Mutalisks are out on the field, Banshees are essentially deadweight. Originally with most Zergs rushing to Infestors, this was not an issue. Now however, the idea that such a heavy tech investment comes with a timer makes the option less and less appealing to most Terrans.
In short, Terrans sacrificed some early game strength in favor of powering their mid game. 2-3 Reapers and 6-8 Hellions became the standard agreed upon numbers of units that Terrans would utilize to harass and delay Zerg macro, while forcing units.
Behind this small, nimble force, Terrans would frantically power out a third command center, fast double upgrades, and a constant stream of bio mine that would eventually parade its way to Zerg’s 4th base.
Zergs, in turn, have adapted to this new Terran style. To defend against the space control squad there are either a handful of slow Roaches or a heavy number of speedlings (30+). Zergs have been going for more Queens for more creep spread, and staying on Hatchery level tech for much longer. A very common build in response to fast 3 OC is typically gasless 3 Hatch, with the 3rd hatchery taken around 6:30. An emphasis on fast upgrades is placed over rushing to the infestor or hive tech. When viewed comparatively, it looks a lot like the Terran side: minimal units to defend, some poking units, a LOT of upgrades and macro, then suddenly a huge swell of units to crush the Terran attack and end the parade.
Recently, however, Apocalypse, a Korean Terran playing for Team Quantic, backed by the Cloak price reduction of patch 2.0.10, unveiled a new hybrid style of Reaper Hellion Banshee. Using the standard ground team of 2 Reapers and 6 Hellions, Apocalypse chose to supplement his force with 3 cloaked Banshees.
To say that the Banshees made a difference would be an understatement.
With their incredible DPS, Apocalypse effortlessly denied the enemy third base multiple times, something that Reapers and Hellions could not easily do because of heavy speedling presence. With creep spread not at the unmorphed 3rd Hatchery yet, no spores could have been constructed to defend it. The Reaper Hellion Squad meant that Queens could not safely traverse off the creep to engage the Banshees. And probably most important of all, the absence of a Lair meant that no Overseers could be produced for some time, giving Apocalypse complete map control. Queens could neither engage the Banshees nor spread creep, forcing the Zerg player back under the safety of his spores and limiting creep spread to the bare minimum.
Behind it, Apocalypse took a fast third command center, went for slightly delayed double upgrades, and powered out a bio mine push that eventually took the game.
Why did this work?
The answer is that it was a very tidy meta game play. Apocalypse went for this build knowing that Zerg would probably not open fast Lair, meaning lack of detection outside the boundaries of his spores. With good Marine positioning and smart building placement, the standard sacrificial Overlord scout did not find the Starport with its glowing green Tech Lab. This enabled Cloaked Banshees to be essentially invincible against their only early game counter: the Queen. Finally, their incredible DPS can easily deny a third, kill Queens and Creep Tumors, and even pick off the occasional transferring drone. And in the event of any sort of Roach-Bane all in, Banshees would have been excellent at picking away at the Roaches as they marched across the map while Apocalypse would simply build multiple bunkers and surround them with SCVs.
In blunt terms, opening Banshees will force a fast Lair. There are no two ways about it: unless Zerg wants to all in or can spread creep extremely quickly to the third and surround it with spore crawlers (which can then be killed by the Reaper Hellion squad), the Zerg player cannot take a third without going Lair against fast Cloaked Banshee play.
And assuming that the Banshee has been successful in repeatedly denying the third, what are Zerg’s options?
They either seem to revolve around an all-in (which should be scouted with Reaper Hellion Banshee and be promptly deflected by good preparation at the Terran natural) or a forced 2 base Mutalisk play to kill off the entire Reaper Hellion Banshee force (which will deplete Zerg’s gas reserves and leave him vulnerable to a bio mine follow up push), or simply start an emergency Lair for an Overseer, which will easily set Zerg back 3 or so minutes, allowing Terran to enter the mid game with a tremendous advantage.
It is important to note that this build will not work on certain maps. Easily secured thirds, especially those with only one entrance, such as on Akilon Wastes or Derelict Watcher, generally restrict the movement of the Reaper Hellion force. The short distance between the bases also allows for very quick Creep connection between the natural base and morphing 3rd hatch for Zerg, which in turn results in the early deployment of spores and spines to fend off the Terran force.
What are the other disadvantages of this build for Terran? In comparison to the damage that the Banshees can potentially do, they seem negligible. Bio upgrades like StimPacks and +1/+1 will be slightly delayed. You will be very behind if Zerg opens with very fast 2 base Mutalisk play, which can potentially end the game if you have no anti air in place. Your third Command Center will also be slightly delayed. When all these factors are combined and examined, Terran is essentially putting everything behind schedule by 1 to 2 minutes in exchange for delaying Zerg for 3 to 4 minutes, or potentially even winning the game if Zerg plays too greedily.
In conclusion, if we see a resurgence of the Banshee in high level TvZ, we could very well see much faster Lairs from Zerg, disrupting early game upgrades and forcing Zergs to be much more conservative about spreading creep, so as to conserve energy for Transfuses. With the new patch at hand, Terran players now have a new affordable option with which to punish Zerg greed.