Frozen orb?

spammed as good ol time.

Its important to note that nextdelay is a timer for each unit, not for each missile/spell or whatever. If an enemy gets struck by a 25 frame delay tornado, it can't be hit by any other nextdelay projectiles for those 25 frames. And the list above doesn't list them all, there are many 'piercing projectiles' in the game- all the zon bow skills, normal bow attacks, thrown weapons and the primary projectiles on javelin skills like lightning fury / plague (not the aoe or secondary projectiles), bone spear, lightning, lightning sentry, etc.
This means that nextdelay skills work quite badly in multiplayer games and have greatly reduced dps. If a trapper and windy are both trying to dps down baal, they'll do massively reduced damage output because the tornados stop the traps from hitting at all
it also means certain effects can limit your damage output, like if your merc has chance to cast tornado
the low nextdelay spells might have very little noticeable effect on each other since the window is so short. In fact, lightning can easily hit targets twice when cast alone by 1 player, because it can overlap monsters more than 5 frames.
however, even when that's the case, spells tend to have both nextdelay and lasthit enabled, so they remember the last unit struck and won't strike that same unit again- lightning will only hit enemies twice when its overlapping two enemies for 5+ frames, so if they're stacked next to each other and you're shooting at a diagonal it can do it. And when that's the case, you effectively double your damage output

there are many skills that don't use nextdelay however. Any projectiles that can't pierce or that deal their damage on every frame. And they all work in multiplayer without clashing with each other
firewall, lightning, firestorm, etc deal their damage each frame
frozen orb, charged strike, fireball, etc are destroyed on collision

there are a few skills I'm uncertain about, like blizzard and lightning fury (the secondary projectiles). They might only have lasthit and not nextdelay, I'm not sure. I think its pretty clear fury can explode enormous amounts of damage on its primary target from all the overlapping projectiles so it can't use nextdelay, but it has to have a means to not deal that damage every frame, right?

Yes, I should have been more specific and said that the NextDelay timer is attached to the unit - sadly, it's too late to edit the post.

I was being a bit lazy regarding "piercing projectiles" - The list there just points out the not-so-obvious things that have the NextDelay property like warcries - but it goes without saying that arrows, throwing weapons etc. fall under the "piercing projectiles" category.

Regarding abilities such as firewall and firestorm and how their missles work, that'll be a separate guide (too messy - have to explain bit rate damage/static missles etc.)

all missiles in d2 are the same object class, and have the same type of collision detection (with different settings for layers of collision)
casting firewall just creates two invisible missiles that move perpendicular to you, and those missiles create a trail of immobile 'fire' missiles, and those fire missiles deal damage each collision check with no nextdelay/lasthit
battle orders like nova just shoots a piercing missile in a whole bunch of angles at once to make a circle, and it has nextdelay enabled or else it would affect you multiple frames in a row- which would be redundant, but probably do nothing if they programmed the hp scaling right

This post was edited by Goomshill on May 22 2019 09:01am

Yeah but this is a guide to NextDelay, not a guide to Missles. And explaining how firewall works is a nightmare.

You would have to explain the concept of distance and unit sizes, how damage is dealt in bits, the different types of missles used by the spell, the effect of cast rate, the effect of firewall vs. monster directionality etc.

What about from dream aura pulses? thunderstorm? static?

This post was edited by hankspimpin on May 22 2019 07:00pm

holy shock doesn't use a missile, it simply deals damage in an aoe once per pulse
thunderstorm creates a missile that locks onto its target and moves with them, hitting only them once, so it has no nextdelay or lasthit
static like holy shock has no missile, its just damage to everything in an aoe