Minefield seems to be adding extra animation time to mine throws that causes mine to be thrown slower, even more slowly than the throw speed penalty on the gem would suggest.I measured the time from which the first mine appears in the upper left corner, to the time the final mine appears in the upper left corner to determine the throw speed. I recorded at 60 FPS and measured the duration frame-by-frame.Ball Lightning + Blastchain Mine Support (lv1/0q)+70% Mine Throwing Speed Modifier16 mines thrown in 2.350sMine Throw Duration: 0.146875sBall Lightning + Blastchain Mine Support (lv1/0q) + Minefield Support (lv1/0q)-40.5% Mine Throwing Speed Modifier4 sets of 5 mines thrown in 2.367sMine Throw Duration: 0.59175sWith a 65% less Mine Throwing Speed modifier of Minefield Support, we would expect to see a mine throwing time of 0.146875 / ( 1 - 0.65 ) = 0.419643s. Instead, we see a throw time that is 41.01% longer.Edit: I've also tested this with a 19/20 Minefield Support gem, the throw time is approximately 40% longer in that case as well.

Speculation as to what's happening here.



Notably, when Minefield Support is socketed the mines from each throw are thrown in sequence. The interval between each throw in the sequence is equal to 10% of the expected total throw time. This "10% of an animation"'s delay, 4 times, produces a total animation whose duration is 40% longer.



This seems to parallel the unsealing of seals generated via the Unleash Support. When a spell is cast, any seals are consumed by appending a casting animation to the original cast that is 10% of the original animation's duration.



Confusingly, this behavior does not occur when using a skill supported by Swift Assembly support. When a proc occurs, any extra mines are thrown instantly at the same time as the first, seemingly with no difference in animation duration.



Now, its possible that this "extra animation" is an intended mechanic. It makes minefield vs swift assembly an actual competitive decision (assembly gives more mines/sec, but minefield is more consistent) and seems to indicate that the developer's had this "extra animation" mechanic in mind when balancing the gems. The parallel to unleash is also a bit uncanny.



Ultimately, its very unclear whether this is intended or not because I've looked in several places and found no documentation of this mechanic whatsoever. It's not explained in-game, it was not mentioned in the pre-blight game balance announcement, it was not mentioned in the 3.7 patch notes, it was not mentioned in the 3.8 patch notes, it is not mentioned on the wiki, Path of Building has this interaction wrong, and I can't find any discussion of this on these forums or on reddit. You would think that if it was intended it would be explained somewhere.