Unpredictable on-death monster one-shots

Grim Dawn Bug Reporting
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I’ve reported this about Naddo, and about Avinnia. I’ve seen it happen with Prodromus, and Jaha Rhinhorn. And now it happened with a random bloodbound hero (Kuld Scarmender) exploding all of his 12 projectiles at once:

This is not a 1 monster problem, it’s a pattern with all of FoA’s monster design. They all destroy all projectiles upon death, at times causing a burst of 40k damage that is completely untelegraphed and (mostly) unpredictable.

I only play softcore but I can imagine how frustrating it would feel to lose a hardcore character just because you “killed them at the wrong time”.

Can we please get a fix where all of these projectiles continue to fly, instead of instantly exploding upon the monster’s death? They are just projectiles after all, not “minions” like Benn’Jahr’s mines.

Thank you Crate for considering this feedback.

Edit: Upon reviewing the footage in slow motion, 11 out of 12 projectiles of the hero to the north also explode instantly when the hero to the south dies. That’s so strange. There might be multiple bugs here.

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Might explain the very nasty burst Voidtorn Rocs - Voidtalons sometimes do. I attributed it to killing more of them at once and eating the death novas, but very well might have been this bug. Nearly 1 shot my HC character out of nowhere.

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So apparently this is not a FoA-exclusive monster design problem. Happens to older mobs too.

This problem also applies to Zarthuzellan even at lower levels.
If you kill him just as he casts his nova fireball attack, all the projectiles explode instantly when he dies and you get an immense amount of fire damage to your face. rip

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*+physial dmg to the face :ok_hand:

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Same as this bug report thread I made a few days ago containing a plethora of other examples. I’m not sure if your example is the same but it sure looks like it, just fine 1 millisecond and dead the next.

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Yep. Looks like it’s the same issue. 3 years… ok so this problem has been around for a while…

Looking at those 2 Twitch clips:
The first case is Glacial Defiler which doesn’t have a nova attack. However, it fires 3 meteors from the sky regularly, and they take some time to travel to the ground. So if 6 or 9 of them are close enough to the player (no matter how high in the sky) and all explode on death, it’s RIP. This was exactly the same way that I died to Jaha; all her chaos meteors exploded on death.

As for the second case, Harros Dread has this:
image
Yep. Nova of 16 projectiles all exploding on death. There’s no surviving that.

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To clarify, based on @Trixx46’s post and Twitch clip(s), this happens as far back as 1.1.9.8.

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@Zantai here’s a scenario that reproduces the bug 100% of the time.
I’m replying here because I could not make it work for Avinnia.
But the same bug triggers very consistently for Naddo.

For a long time I couldn’t reproduce the bug. Timing was not enough.
I was using DPYes to teleport straight to Naddo, and killing him mid-sunder waves, but none of his projectiles exploded on death. (45s game sessions)

Later I remembered that strange things start happening in longer game sessions. Maybe that could have an influence in this bug too. So I simulated a “normal” long game session and went towards Naddo without using DPYes’ teleports, and bingo. Bug happened in 4 runs out of 4. (7m game sessions)

The trick to reproducing the bug is having a long game session going.

Steps to reproduce:

Test char: projectile-bug-tester.zip (1.8 MB)

  • Start the game on Ultimate with the test char “Primal Sinner”, and shapeshift into Werewolf
  • Use only Feral claws + potions + Rallying Cry, and no other skills. Everything you need is on the skill bar.
  • Important: For the next 2 steps simulate a normal playing session. Kill some of the monsters on your way. Pickup some of items on the ground. Destroy some bone piles. Click on chests and loot some dead bodies. Find the Treasure Trove and do the Totem. Should take around 7 minutes total.
  • Teleport to the Black Citadel and go kill Gruldir
  • Move into The World Tear and go meet Naddo
  • When you reach Naddo, hit him until he’s at about 10% health.
  • Wait for him to start a Sunder attack, and kill him mid-way through the multi-waves of sunder projectiles.

If you get the timing right (videos below can help), you should see several of his projectiles explode immediately upon death. The longer the game session, the more projectiles are likely to explode.

Video of bug never happening for me:

DPYes teleported straight to Naddo, left him at 10% health, and killed him mid-sunder. I repeated this test some 10 times. Could not reproduce in 45s game session.

In case it matters, here’s the teleport list file I’m using:
GrimInternals_TeleportList.txt (838 Bytes)
The Naddo teleport requires cheats enabled (no rifts area).

Video of bug always happening for me:

Did 4 runs of “normal” long game sessions without DPYes. Ran into Naddo’s dungeon, killing things and grabbing loot along the way. Bug reproduced 100% of the time. Skip to 7:15 on the video to see it happening; upon his death, 8 out of 10 of the mid-air projectiles explode, dealing 22k damage, and 2 continued flying.

Curiously, in one of these runs I ignored the Trove and the Totem and ran straight into Naddo at about 4 minutes time. When I killed him, only about 4 of his projectiles exploded. The majority continued flying. It seems the longer the game session, the higher the probability of some random projectile exploding? Which matches the observation on the first post of this thread: an enemy dying and projectiles from a different enemy exploding.

It also looks like the projectiles that do explode are the closest to the position of the enemy that died, and the projectiles that continue flying are the farthest frontier.

The cause? No idea. This is all very strange behavior. Maybe a memory leak or memory corruption that’s making random projectiles explode upon a monsters death?

Anyway I hope that reproducing this with dev tools can shed some light on the real cause.
Lmk if there’s anything else I can help with.

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You are a legend among (wo)men.

Minor addition - when my character exploded it was on a farm run for Prodromus, killing nothing but the last batch of bloodbound along the way. So it starts happening well before the 7 minute mark, as that entire run was only a couple minutes at most.

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I’ve been rather successful in recreating this using a mod (playing via proton).

My setup is this: spawning a copy of Slatsarr, that only uses it’s 14 projectile nova skill and killing it with doombolt mid cast animation. In the mod the nova skill projectile have a explosion radius of 8 (or maybe 16 don’t remember now), rather than the default 2-ish.
The character has an item giving it enough damage to one shot Slatsarr, a bit OA and DA, damage immunity to all but fire, lots of speed to better time the kill.

Mod items/monsters:
test/dev_belt_dmg.dbr
test/basilisk.dbr
test/basilisk_fast.dbr (fast animation version)
test/basilisk_slow.dbr (slow animation version)

Adding mod, char and video.
InstaDeath.zip (283.8 KB)
_ProjEater.zip (141.1 KB)

(the video is based on the default 2m projectile explosion)

  • 0:08 walking into boss, casting doombolt. Projectiles to the north explode.
  • 0:25 far distance kill, all projectiles explode. Char not hit before kill
  • 0:34 short distance kill, all projectiles explode. Char got hit before kill
  • 0:48,1:00 short distance kill, all projectiles explode, but character does not get damaged. A speculation here, but perhaps an initial DA roll prevented the char from being hit by all explosions. Or was not in range of explosions.
  • 1:12 works normally
    About 10-ish more instances follow in the video, but the fall into one of the above.

I’ve not noticed any correlation between long/short play sessions, needing to kill anything else, the character already being hit by one projectile, not being hit by any projectiles, long/close kill distance. I can restart the game, load into DC and first boss spawn have the bug happen.

I’ve toyed with the death settings: disolve, corpse + corpse persistence setting, Slatsarr’s nova projectile settings - the bug still happens.

Only killing the boss, mid animation. I was not able to get the bug on the fast animation version after it’s animation ends (so far). And it’s not consistent, sometimes I can replicate like 5+ times in a row, sometimes it’s 1 in 10.

And regarding the explosion spreading to other projectiles from another enemy (like in OP video), I was able to observe it once with two Slatsarrs on the field when one dies, but never got it replicated or on video.

Let me know if any other details are needed.

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So this might be how Ekket’Zul killed me (Another episode of “Why did I die?”). Just like I said: nuke-on-death. Knew I wasn’t crazy. Thank you.

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We have identified the most likely culprit for this issue as a rare case where the projectiles can intersect with the resulting loot orb, triggering a synchronized eruption. This issue would have been in the game since the very beginning.

We will push this fix out in an upcoming small update and hopefully that will be the end of it. Thanks for the detailed sleuthing!

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yeah, outstanding efforts guys

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Damn, the cause of all the BS deaths over all those years has finally been found and (hopefully) eradicated! :partying_face:

GG WP and thank you to everyone involved!

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There might still be the collision detection bump “bug” between hero/boss and player at time of Nova cast causing insta death that some have also had.
This seems much rare but happens without the enemy dying, and again has been around like forever.

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insane work, gg boyz

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Just leave it to Coincident to find ways to facerocket in other games besides DOOM… :upside_down_face:

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