Rack-Running w/Hydra


Diabloii.Net Member
Very quickly, rack drops are affected by map seed, which AFAIK is in turn affected by:
  1. Monsters spawned
  2. Monsters "alerted" and/or route taken to a rack
  3. Touching rack vs. using TK
  4. Casting Valkyrie/Golems?/Hydra
  • The placement of Hydra on/above/below rack etc will alter drop
  • The number of Hydras will also alter drop
This may be common knowledge, and I'm just a dunce. But, I wanted to put it out there just in case. I have noticed over my 1000s of rack runs that the Hydra "formation" would occasionally get altered. And, I would know beforehand that a rack wasn't going to drop what I wanted because the Hydra looked different.

Again, I feel kinda stupid for never putting this to use before now. But, this can be used to your advantage:

Scenario A: (my typical Russet Armor rack) will ALWAYS drop Russet Armor after 3x Hydra with this "formation".
Hydra #1 ALWAYS looks like this (12:00, 2:00, 4:00)
Hydras #2 and #3 ALWAYS look like this (additional head at 7:00)

Scenario B: (deviation from Scenario A) Because of Hydra #1 formation, I know that 3x Hydra will FAIL Russet Armor Drop. I kept seeing this same deviant formation, and eventually found out that 5x Hydra will also drop Russet Armor.
Hydra #1 (formation is at 11:00, 12:00 and 1:00)
Hydras #2 through #5 (additional head at 8:00)

The Hydra "formation" is a reflection of the current map seed. Using this info, you should be able to work "unstable" racks into having multiple useful stable drops.
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Diabloii.Net Member
Good stuff! I was looking into that a little bit back in September 2017 when I was doing some racking in 1.07. Never continued that "research" though as the rack runs were taking away my sanity. :D But I guess I'll quote the post I made about it for reference, with my findings on the cast location of summons:
And something regarding racking..
Not sure if this was known, I could not find info on this specific thing.
A bit of a wall, so spoiler tags:
The orange circles below are points where you can cast a summon, but it can not spawn there. In stead, it will spawn at a near "valid" point.
The blue circle is just a regular point, nothing special about it.

To the rack, for some reason, there's a difference. If I'd cast a Decoy at blue, the rack will tick 1X, but if I'd cast a Decoy at orange, the rack will tick 1Y. For this particular rack, this means it changes from a Maul to a Throwing Axe, or from a Maul to a Military Pick.

As for the Hydra, since it spawns three separate "entities" or whatever, it will tick the rack three times.
If I would have casted the Hydra at blue, the rack would've ticked 3X, but since I casted in the corner, two of the heads were pushed from "invalid" to "valid" spawn points, which ticked the rack for 2Y. One head was able to spawn where it was "meant to spawn", so 1X from that one.

And for example casting a Golem at the spot where your current Golem is, will tick the rack for 1Y, and not 1X. This probably counts for all summons, except for..
Hydra seems to be an exception to this, I suppose because they have no collision.

Edit: Forgot to mention that you yourself are of course also an entity with a collision, meaning casting a Golem or whatever on your own location will tick the rack 1Y.

Note that the order does not matter: 1Y + 1X is the same as 1X + 1Y. While this limits possibilities, it does tell us a little bit more about what's going on.

This can open up quite a few extra possibilities, depending on your class/skills.

Below's a list of skills that I've tested that will tick racks. Blade Sentinel always ticks the rack 1Y for whatever reason, perhaps because it spawns on your own location.
Bone Wall specifically is awkward because it spawns between 5, 7 or 9 segments depending on slvl and, I guess because of how their spawns are handled, it's not very reliable from my experience.
I haven't tested summons that require a corpse :p

clay golem
blood golem
iron golem
fire golem
bone wall (each segment)
hydra (each head)
blade sentinel (always invalid)
shadow master
shadow warrior
traps from assassin
traps from shadow warrior / master
all druid summons
I've debugged it a little bit since then, but since it's possible that newer patches seed racks differently from the patches I've checked this in, I'll try to refrain from too many details.

The rack functions use the seeds of the segment that the rack is on:
Each of the segments that an area consists of has its own set of (2) seeds, and this set is updated whenever a unit is created on that segment. And by unit, I don't just mean monster, it also means object, item, and missile.
Since objects are included, Town Portals also affect this set of seeds, and since items are included, opening a chest, killing an enemy, or using another rack, can all affect this set of seeds.
So when you finally pop a rack, the RNG will use a set of seeds that was changed every time a unit was created on that segment.

Edit: By segments, I mean the bigger chunks that areas consist of, Albatross his Ancient Tunnels guide shows this well.

Then the running/routing part: As a player you kind of have this big aura around you that will (re)spawn segments if you get within range (or de-spawn them if you get outside of range). It looked to me like every existing segment has its set of seeds updated whenever another segment is (re)spawned anywhere in the game.
So, changing your route might mean spawning segments that didn't spawn in your prior runs, causing the set of seeds that's ultimately used for your rack(s) to be different.

I don't know if missiles still affect the set of seeds in later patches, but that could be an explanation to the inconsistencies that have been experienced. Because casting a single Orb, Nova or Frost Nova means that this set of seeds gets updated dozens of times -- once for each missile created.
If that is still the case in later patches, then things like Cast Frost Nova when struck, mercenaries shooting missiles, and enemies shooting missiles can all affect racks (besides of course your own missiles).

Well.. maybe not such useful info since I don't know if this is still how it works in later patches, but it's a small reference I guess. :p I do assume that the general idea still applies to 1.14, but perhaps some specifics have changed.

Edit: Worth noting is that timing can also affect things, since the spawning of segments is not necessarily instantaneous.
What I mean is, let's say you use Teleport and it causes your "aura" to reach far enough for 5 new segments to be spawned, it may take a few seconds for all of them to have spawned. So if you quickly teleport to the rack and click it, you might get a different result from when you teleport to the rack, wait a few seconds, and then click the rack.
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Moderator Single Player
The Magic Line (as mentioned by Grip in his Trav write ups) is also very important. If you take a route slightly to one side of the rack you get one item, the other side you get a different one.

I rarely run a rack that takes more than five teleports. The extra distance means more spawns so more instability.


Moderator Single Player
A better explanation:

From the spawn at the waypoint to the hut with a weapon rack. The straight route is the magic line. Tele along this route and the rack is unstable.

Tele to the left of the magic line and the rack consistenlt drops Greater Talons.

Tele to the right and it drops Rune Swords


Diabloii.Net Member
This is what my map looks like:
107 Racks.jpg

Most paths require 0, or 1 Hydra to force desired drop. So, I didn't bother marking it all down. The example I used above follows Scenario A 80-90% of the time. But, rather than just waste the other 10-20% of runs, I figured out Scenario B that will make good use of those runs. ;)


Diabloii.Net Member
One thing worth mentioning is that the location of hydra also affects the drop so plopping it right on top might be hard to be consistent with, but dropping it at a certain spot around the rack might make it easier to be more consistent.

Thanks for the research!

I think the biggest take-away is for people with really good Lk maps, but no good default racks. In that case it might be worth playing with little tweaks to manipulate the racks into dropping desired items.


Diabloii.Net Member
Thanks! As someone who plays 1.14 only, are there any differences between e.g. 1.07 and current patch D2? I have also made of the observations you made, but I’ve read somewhere that racks behaved differently in earlier patches. Do they? :)


Diabloii.Net Member
I’ve read somewhere that racks behaved differently in earlier patches. Do they? :)
Well, I've just gone over it a bit, and a lot from my prior post does not apply to 1.14. Missiles for example certainly don't affect racks. Town Portals still can, but only once apparently? Not quite sure what the deal is.
Racks still use the same set of seeds (those of the segment).
Monster creation still affects racks, and still only when they were created on the same segment as the rack. So casting any of the summons will work for sure, but not if they are created on another segment.
Edit: Forgot to add that item creation also does not affect racks in 1.14. Using a trapped object does, it seems. :p

To give you an idea, here to the top-right is where the armor stand is located.
I've cast Hydra twice: The bottom cast did not affect the rack, since those heads were created on a different segment. The top cast however affected the rack a bunch of times (9). Each head affects the rack separately, because Hydra essentially creates 3 monsters.

Edit: Not sure how to shrink the image size so I'll just spoiler it up:

Each monster updates the seeds 3 times (well, the summons that I've tested, at least).
When cast on an "invalid" location, a monster updates the seed an additional 4 times. Haven't checked why, but I assume it's because the game needs to do additional RNG rolls to determine where the monster should spawn.

The reason that seeds gets updated like this is because whenever a set of seeds is used, it is also updated. Obviously this is done to keep things random. :)
So a rack for example will use the segment's seeds, and then the rack will update the segment's seeds. This is why one rack can affect another rack, if they are on the same segment.

I suspect that 1.07 and 1.14 are very similar, if not exactly the same. The RNG in 1.14 is much less aggressive for racks than it is in pre-LoD patches, as the segment's seeds are updated way less often.

Segment seeds still get updated as you move around, just like in 1.07, but I don't know why that is exactly. It's definitely different from pre-LoD, and the updating also happens way less frequently.

Well, that's all I had for now. It's only a small portion of the story of course, but from a glance, it does look like 1.14 is as stable/predictable as 1.07 is.
Not sure why you'd rack in 1.14 though, weren't the chances for uniques and sets terrible there? Maybe even non-existent? :p
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Diabloii.Net Member
Well, that's all I had for now. It's only a small portion of the story of course, but from a glance, it does look like 1.14 is as stable/predictable as 1.07 is.
Not sure why you'd rack in 1.14 though, weren't the chances for uniques and sets terrible there? Maybe even non-existent? :p
Hey now, my untwinked tournay barb has racked tens of infernap caps, a few biggins bonnets and a pair of titans!


Diabloii.Net Member
I figured this was the most appropriate thread for this. Question to @Fruit and other specialists.

Currently running LK with an untwinked Pally to farm Enigma. There are two choices in (literally) running LK, namely either going back to WP and A4 or running through the A3 docks. So I compared them to see whether on my specific map it is faster to go to A4 or run through town in A3.

I was very surprised that this seemed to affect one armor rack next to the WP. It drops Battle Boots (which I like for the chance of getting WT) when I came from A4, whereas it drops Ornate Plates when I'm coming from A3. Of course in each case provided there are no other monsters around. I continued to pay attention to this using both A3 and A4 routes, and by now I can safely rule out any other possibility – the drop is affected by which area I'm coming from. In particular, the movement pattern after entering LK is not decisive. I could never get it to drop Battle Boots unless I came from A4.

Is this a known fact? And more importantly – does anyone know whether this apply to other spawns as well? I knew that teleport paths can change spawning regarding both racks and in some cases monsters, e.g. in Travincal. But I never thought it possible that any action that was performed before entering the target area had any effect. For example a similar question is boss spawning on Pit maps which can change quite a bit. While I was pretty sure it wasn't due to teleport path in the Pit, I'm wondering whether any action before entering the Pit affects the spawn.


Diabloii.Net Member
Very nice breakthrough ffs! If a person finds a rack 1 teleport from the wp, it might be worth checking "entering" from a1, a4, and maybe a5 since all those wps are relatively close to spawn.


Diabloii.Net Member
talking about monster spawns in the pit, maybe there’s a difference going through the cloister vs black marsh. Would be fairly easy to check


Diabloii.Net Member
@Bobbo @ffs I dont think it will affect the pits. I believe the reason that it affects LK (if confirmed) is because the "entrance" (the WP) is coming in a different way. With the pits, you are still coming into it from the same place (Tamoe). If stuff exterior to map with the racks affected the random seed, I feel like we would have noticed, but maybe not? shrugs. Here's hoping @Fruit can shed some light for us :)


Diabloii.Net Member
Well, whenever at least I think about how racks roll in a more consistent manner, I’m doing runs as consistent as possible. If I run all over the place I probably don’t think about the rack contents.

Suppose there’s some kind of global seed that’s affected by basically anything that happens within one game, it could be affected by anything from entrance points to Which areas are passed through or which npc’s have been talked to. I don’t think it’s _that_ global. But it’s something to think about at least


Diabloii.Net Member
I ran and tested some more. First I wanted to confirm it's really just about where I'm coming from, so tested S&Eing in A1, A2 and A4, starting the run there, going to Kurast Docks and then to LK. Result was Ornate Plate again in all cases. In other words, where I start (or end) the run does not affect the rack drop, but only whether I'm coming from A3 or not.

Also tested entering LK from A1 and A2. In both cases it dropped Battle Boots. I cannot test A5 on this map because I haven't quested there yet, but seems it drops Battle Boots when coming from either A1, A2 or A4, whereas it drops Ornate Plates (only) when coming from anywhere in A3. (I also tested A4 -> Travincal -> LK. Still Ornate Plate.)

Moreover, along the lines of what @sir_cyclops hypothesized, any movement behaviour before entering LK has no effect whatsoever. Feeling silly, I ran around in various patterns before hitting the WP to go to LK :D but the drops remained as described.

I have not yet tested this with other characters. But if it's a general pattern that might make finding racks for specific item types easier. I'm especially curious whether this works in 1.07 as well, can somebody test this? I don't time-travel or even play older patches at this point, but if it generally behaves that way even in 1.07 I can only imagine it could help a lot with finding those Ark's etc.


Diabloii.Net Member
I too tested a bit, I couldn’t see much difference in coming from a3 or a4 straight into LK. I guess I need to test a bit more, but I can’t get much difference at least. Interesting that we see
Different results

Thinking about it, my current map feels unusually stable when it comes to movement patterns, it’s still cycling the racks if I do large movement changes and if I pop things/kill stuff but it’s not as sensitive to small movement changes as some maps are (or maybe it’s just my memory of older maps playing tricks on me)


Diabloii.Net Member
Ok, so I jumped the gun a bit. Seems I do get different results, some things I can only rack going from a3 and some only going from a4. Depending on corpses etc popped though, there seems to be some overlap in my possible results.


Diabloii.Net Member
Wowwww. It just hit me that this is HUGE information for characters who don’t have enigma (aka most of 1.07 non sorc). Since you’d be entering from act 1 when rerolling, but running from act 3 when rerunning. I bet this has been the bane of many people racking.