Hello – my name’s Crimson, and I speedrun the D4 campaign. I have killed campaign Lilith more than 50 times, and completed Act 1 at least 150 times. This is a list of reproducible bugs in the campaign – since I figure many of the same escort/follow/fetch quest types will be used in the expansion, I figured I’d put this here for the benefit of the devs. I can provide video clipped examples of all of these.
Act 1:
While in the Cradle, pursuing Lilith, you and Neyrelle will enter the last room before going to the Vhenard fight. If you enter that room too far ahead of Neyrelle, and she’s mid-fight with a mob when the game rubber-bands her to you, she can completely de-spawn and you will be unable to complete the dungeon. The only way to resolve the issue is to exit the game and re-load, which requires re-running the dungeon.
In the room after the first blood petal interaction where you see Lilith/Vhenard talking, it is possible to softlock yourself with both Barbarian Leap and Sorceror Teleport, ending up underneath the floor geometry.
Act 2:
Upon arriving at Firebreak Manor, there is a consistent “loading zone” that presents consistent, uncomfortable lag.
Yorin (and many other follow characters) can be impeded from arriving at fixed locations where he wants to stand. If you body-block him from standing at his preferred location in front of a door he wants to unlock within the Cairns, he can end up spinning in place, and never arrives at the fixed location he likes. You will never be presented the dialogue option which requires you to fetch the stone to allow him to open the door.
Upon exiting the Eldhaime keep combat dungeon (before you rendezvous with Donan in the great hall), there is a consistent “loading zone” that presents major lab consistently.
When advancing through the second half of the Eldhaime Keep arc (escorting Donan to the soulstone’s location) there is a door that is consistently bugged, where it visually shows but cannot be interacted with, and is no impediment – you just need to run straight through the closed door.
Act 3:
When you enter the temple of the triune, Lorath frequently will end up standing just inside the door, and will not walk with you through the dungeon. Because Lorath’s voiceline/position is the trigger for the spawn of the named Elite Balrog at the first dungeon checkpoint, this prevents advancement through the dungeon. Teleporting to town and back into the dungeon generally, but not consistently, will resolve the issue.
Upon exiting the exit dungeon from the Ghuulan sewers (after slaying Mother’s Judgment), and running toward Mt. Civo to rendezvous with Lorath, there is a consistent “Loading Zone” that presents considerable lag.
When following Meshif through the sandstorm, it is possible to teleport to town and back. This allows you to duplicate Lorath, as well as to, quite oddly, mute all character voicelines temporarily.
After slaying Brol and advancing toward Tarsarak, there is a consistent “loading zone” that presents considerable lag and rubber banding.
Act 4:
When escorting Donan through the Horadric Vault, he will frequently (especially at his third desk) remain in his “combat” stance and refuse to collect his amulet and final notes.
Act 5:
If you stand on Valtha’s fixed position, she can encounter the spin-in-place issue as Yorin. The only solution, as with Yorin, is to exit the game and re-load.
When in The Ritual Grounds and inside the hut with Taissa, the hitbox for clicking on her to progress the quest dialogue is substantially misaligned with her character model – the hitbox is in the location she would be if she were standing ~50cm behind where she is kneeling.
At multiple locations in the quest progression in Act 5 (upon completing the Donan-Soulstone, Lorath-Finger, and Elias-Kill portions) there is a period of 5-8 seconds where teleporting to another waypoint is impossible, while the game is updating the quest progression flag (?). If you time it just right, your teleport will place you at a waypoint other than the one you chose. On one occasion, a waypoint teleport I used deleted my quest progress.
Act 6:
After Duriel, there is a consistent “loading zone” en route to rendezvous with your allies before entering Hell.
There are a small handful of other, non-game-breaking reproducible “bugs” that are hard to implement, may constitute intended behavior, and benefit my speedruns, but I can explain them if devs are curious.
Some of these bugs (notably the body-blocking of characters that want to advance to a fixed position, the waypoint bugs, the “loading zone” lag and rubber banding areas, and the Lorath follow-breaking inside Mt. Civo) occur repeatedly and in multiple places, indicating that the underlying mechanic that’s used in multiple locations has some consistent fault. There are ways to play around these issues, but they require knowledge of the underlying game mechanic (and, in some cases, pre-emptive action on the part of the player).
Also, this isn’t a bug, but there is a LOT of latency between certain plot voicelines in the campaign – e.g. with Yorin inside the Cairns where the ancestors are talking and he reads the elegy written by Airidah, there is easily 5+ seconds of total, immersion-breaking, bizarre gaps between voice lines. The same is true of multiple locations within the campaign. Another example is in the Vision of Travincal, where Mephisto will bizarrely pause between voice lines in a way no real human would.