Preface
Hey there folks!
I think it's fair to say that creeping barrage abilities in CoH2 have always been kind of an odd and situational feature of the game. While they can be quite useful in some scenarios, people usually prefer to use the good ol' trusted regular barrage instead, at least where it's available.
Probably one of the reasons for this is that it's kind of hard to predict where the shells fired during a creeping barrage will hit, and at first glance the UI indicator doesn't seem to particularly helpful with that, either. Plus, why spend 30ish munitions for an ability if you can achieve the same results for free, right?
Wrong! Well... at least in some cases, and the following little tutorial is aimed at demonstrating where creeping barrages differ from their regular counterparts and how this can be used to squeeze out that extra bit of damage and reliability.
To get there, it's probably best to quickly recap how creeping barrages work, in particular what defines the scatter patterns of the shells/rockets fired.
Basics
Everyone who has ever used a creeping barrage will likely be familiar with how to aim one in order to roughly hit the desired target area; just click to set the center of the targeting indicator and rotate the box in the direction you want the impacts to creep towards. Quite simple indeed and not much different from placing a regular barrage! But where will the projectiles land exactly?
For normal barrages, this is defined by the values for angular and horizontal scatter (plus a couple of modifiers thereof), which usually increase with distance between shooter and target. However, for creeping barrages things are a bit different.
Here, an additional box is drawn around the target indicator which is further subdivided into smaller sections that inscribes all possible impact coordinates for one ore more shells/rockets of a creeping barrage. These sections activate after a given number of projectiles have been fired (or a specified time interval) causing the "creep" effect of the ability. Within these active sections, a random point is chosen where the projectile(s) will land which defines the scatter of the ability. Although, technically, normal range-dependent scatter is layered on top of this creeping barrage scatter the effect is usually negligible, as most creeping barrage projectiles have been standardized to have very little to no regular scatter at all (in fact the Katyusha's creeping barrage used to have abnormally high regular scatter prior to the most recent patch, making the ability almost worthless in the past).
The actual dimensions of the scatter box and number of subsections can easily be found in the attribute editor for each creeping barrage ability - although with a twist.
As depicted in the graph below, the most straightforward way to interpret these values would be to construct a rectangle with the given x and y coordinates (say x = 5 and y = 20) with the pivot point right in the middle and divide it into the given number of subsections (e.g. n = 4 in this case) (Fig. 1, left panel). However, this isn't quite how it works in-game. Instead, for some obscure reason the box is first divided into n-1 sections (i.e. 3 in the example) and an additional section is appended to the top of the box (Fig. 1, right panel). This not only makes the scatter box a bit larger (exactly n/(n-1) times) but also shifts the pivot point downwards a bit. As a result, the shell/rocket impacts don't quite line up with the UI indicator as one would expect.
Fig. 1
Still, that's that's not the only and by far not the most important way the behavior of creeping barrages differs from what would be expected in theory. In fact Brosras pointed out
a while ago here that the very first rocket in the Stuka creeping barrage seems to always hit exactly the same spot with no apparent scatter at all.
the very first projectile, always lying between the 3rd and 4th bands, the rest of the shells are random
After a bit of research and modding on my side I can say with some confidence that this is indeed a bug/feature affecting all creeping barrage abilities and the very first projectile always impacts right in the middle of the lower boundary of the scatter box (Fig. 2).
Fig. 2
Given that this allows the player to place a quasi precision-strike-accurate shell anywhere on the map the question is now: Should this be considered a bug that needs fixing or is the impact so negligible that it could remain in the game as an interesting quirk making creeping barrages slightly more useful?
With this out of the way, let's get to advertised tips & tricks section that will hopefully help some of you to place these barrages a bit more efficiently. To do so, I've lined up the scatter box and active sections for the Stuka's, Priest's and Sexton's creeping barrage ability with the respective in-game UI indicators, which should make it easier to predict where exactly the rockets/shells will land.
1) Stuka zu Fuss
While the width of the Stuka's scatter area actually lines up pretty nicely with the indicator, the length is off by quite a large margin. As you can see in the picture below (Fig. 3), the first rocket will always land on top of the 3rd chevron with pinpoint accuracy. The rest of the rockets will impact at a random point within each of the designated rectangles (e.g. rocket #2 in the rectangle between chevron 7-9, #3 within chevron 10-12, etc). Hence, in order to score a precision strike simply align the 3rd chevron with the target and fire away - that's it.
Fig. 3
2) Priest
For the Priest's creeping barrage (Fig. 4) the situation is somewhat similar to that of the Stuka: the UI indicator is pretty accurate in the x-, but not so much in the y-direction. The first shell will land pretty close to the tip of the 2nd chevron, while the rest will scatter somewhere between the 3rd and the last. One particular advantage over the regular barrage is undoubtedly the small scatter area of the creeping barrage. Its size is further not dependent on distance to target and not affected by FoW scatter multipliers. Hence, outside of close-range barrages with vision the normal barrage will practically always have greater scatter than the creeping barrage, so the latter is preferable most of the time even if you don't want to (ab)use the perfectly accurate first shell.
Fig. 4
3) Sexton
The last arty piece out of the bunch is somewhat special in that it has not only one pin-point accurate shell, but four for 4 x the fun! To balance things out a bit (i guess) it also has a bit of range-dependent scatter on top of that defined by the creeping barrage scatter box, so these four shells will be a bit less accurate at longer distances (and if fired into the FoW). The length of the scatter box (Fig. 5) is further pretty large (66.7 m), making it difficult or even impossible to get all shells hitting a target of interest and greatly limiting the use you can get out of the ability. FWIW, the accurate first and 7th shell will land more or less close to the middle of the semicircle capping the upper and lower parts of the UI indicator, while the 3rd and 5th impact close to the 4th and 10th chevron. The even-numbered shells can scatter anywhere in between the previous and next accurate ones, so it is possible (though not really likely) to get two or even three shells striking the same target if the RNG gods are kind. Still, the regular barrage will usually be preferable unless you somehow manage to align all precise shells with juicy targets.
Fig. 5
4) Katyusha
ETA Delayed...
Since the mod tools haven't yet been updated as of writing this up, I'm not sure what solution the balance team came up with to fix the scatter of the Katy's CB. Will update this section once I have more info.
Conclusion
Hopefully this little guide could provide a bit of explanation to how creeping barrages work and how to use their peculiar features to your advantage. And, most importantly, I hope all of you now feel prepared to answer the poll question to the best of your knowledge!
Anything important I've missed or you'd like covered - let me know.
-MMX-
Relic Entertainment
cblanco ★ 
보드카 중대 
VonManteuffel 
Heartless Jäger 
