Elemental Attacks and Status Effects

This post grew out of a discussion on Discord and is intended to serve as both a summary of this conversation and beyond that as a collection of the things we know - and don’t know - about elemental attacks and the status effects (SFX) they can cause.

What we know

Each status effect is associated with a damage type and has two requirements for triggering:

  • An attack with this damage type must hit the mob or player (not just the shields).
  • The attack must have some matching elemental attack strength.

Stun is caused by Physical damage and prevents movement and attacking.
Ignite is caused by Fire damage and causes the loss of 3% of maximum hitpoints per second.
Shock is caused by Electric damage and prevents most skill use. It also causes damage that seems to increase with each second that the shock status is active.
Poison is caused by Toxic damage, causes minor health loss over time and prevents most health regeneration from working.
Phase is caused by Spectral damage and reduces the damage output by 50% while increasing damage taken by 50%.

For example, your attack must deal Physical damage and have a greater than 0 Stun attack strength to be able to cause a mob to be stunned.

Increasing the elemental attack strength makes it more likely for the status effect to proc, provided the stated requirements are met.

And that’s basically it for sure knowledge.

What has been observed

Weapon attacks with a high rate of fire (ROF) seem to proc status effects more reliably over a given time period than slower attacks. Most exceptions, like the Templars’ Nova guns, are suspected or known to behave in unintended ways.

The proc chance for status effects on high level mobs like level 59 mobs in Churchyard or Nightmare Sydonai at level 62, seems to be lower than can be explained by any known or previously proposed formula.

When you look at your focus, it has a field named “All Elemental Effects Attack Strength”. This value applies only to the skill you are using. If you are using a skill that has no inherent elemental attack then it does nothing.
You can’t add 5% spectral damage on a Mortal Domain (“All Elemental Effects Attack Strength 350”) and use Flameshards to proc phase. You would still need to add phase mods to do that. – aladinf (Source)

What have other people said about this

The test results and speculations in this section all relate to other versions of this game and may or may not apply to London 2038. While it is likely that most of the basic mechanics are the same across all versions of the game, this is by no means guaranteed.

Harrowing about Hellgate: London SP 1.2 (Source)

In simple form the game decides elemental effects by taking the attack strengths (post armor reductions) and dividing them by elemental defense values. This results in a direct percentage chance to occur. For instance a 20 ignite based attack would have a 20% chance of procing ignite if it hits a 100 elemental defense monster. If a value greater than 1 is returned from this equation[…] ( i.e. an ignite attack of 110 hitting 100 defense), that elemental chance gets hard locked at 75% or (0.75) My single wield tests have shown this.

In dual wield mode that chance gets multiplied by 0.6 returning a 45% chance to proc the same effect.
What isn’t expected is the result of separating the elemental source from the attack strength relics into each focus. That 45% chance gets reduced even further… I’ve tested this and it happens only about 20% of the time.

While I respect Harrowing for his diligent efforts in trying to make sense of the game mechanics, I have my doubts about these findings since they do not seem to be borne out by experience in 2038 - mine and others’: aladinf reports being unable to verify the Focus dual wield results, for example. The proposed proc chance calculation also leads to probabilities that are much, much higher than observed and not just against high level mobs.

Harrowing quoted by BlueSunshine about Hellgate London SP (Source)

it would appear that elemental strengths are now affected by critical damage as well. 1 relic in my off hand was a 3% physical and 48 stun attack strength. Apparently this relic as the single source of elemental attack strength with only 1 12% elemental attack strength multiplier was enough to force any spectral target which survived a critical hit to have a stun animation that would last for 2-3 seconds. 48 stun attack strength does nothing against level 50 spectrals, However simply if a critical hit occurred and the monster didn’t die, that stun attack strength was very very high.

This is the first and only time I’ve heard about a link between critical hits (or damage output) and SFX procs. As such I am, again, doubtful.

MadScientist about Hellgate: London SP 1.0 and Hellgate: Global (Source)

The base probability that an effect will trigger is given by p = a / (a ​​+ d) , where a is the effect’s attack strength, d is the corresponding defense.

Mickey the Marksman shoots Zachary the Zombie with a Fusion Rifle with Ignite Strength 800. Zachary has an Ignite Defense of 200. The base Ignite probability is 800/(800+200) = 0.8 = 80%.
Each weapon has an SFX factor that is multiplied by the base probability. The higher a weapon’s attack rate, the lower its SFX factor. Typically weapons with 1 attack per second (i.e. 60 rounds per minute) have a factor of 1, slower weapons higher and faster ones lower (usually 1/(number of projectiles per second)). The exact values ​​are defined in a table.

A “normal” level x monster has an SFX defense of 100+25*x. This base value is scaled for each monster type. Most monsters have a scaling factor of 100%. A few exceptions:

Stun defense: Gargantua 500%, Juggernaut 500%, Vortex Goliath 300%, Zombies 50%
Fire defense: Tormentor 500%, Gremlins 200%, most necros 50%, Zombies 10%
Shock defense: Vortex, Blade and Shock monsters 200%, Carnagors, Hulk monsters, flying angels 50%
Phase defense: Orbiles, Zombie Summoner, Furies 200%, Imp, Gremlin, Darkspawn, Riftwarrior, Shock, Blade monsters 50%
Poison defense: Necros 200-300%, Orbiles, Diabolists 50%

This is corroborated in part by entries in the wiki at hellgateaus.info. The relevant entries are

  • Damage which has the formula for the base probability,
  • Monster Levels which has the monster base SFX defense per level.

The entry about Champions may be relevant in that it does not mention an effect of monster rank (e.g. rare, legendary, unique) on SFX defense strength, but does mention boosts for mind change (e.g. Fear and mind control weapons) and interrupt defense. Bryan also vaguely recollects that monster rank has no influence on SFX defense.

What I suspect is going on

  • The base probability formula is correct, meaning that p = a / (a ​​+ d) , where a is the effect’s attack strength, d is the corresponding defense. Reason: it is simple, computationally cheap and provides built-in diminishing returns and a limitation to values between 0 and 1, i.e. 0% and 100%. A formula like this is apparently also used to calculate the damage reduction from armor.
  • The ROF/attack rate adjustment, while it was talked about on the dev forum of Flagship Studios, seems not to work. Or if it does, it is insufficient. Reason: observed behaviour clearly says that high-ROF weapon are better at inflicting status effects. A working attack rate adjustment should prevent this.
  • There likely is additional level scaling involved that is responsible for the poor proc chance for SFX on high level mobs. From the severity of the performance decline against high level mobs, it may be similar to the level scaling for Experience (see Experience on the london2038 wiki) Reason: it’s the simplest, computationally cheapest mechanic that I can think of to explain the observed behaviour against high level mobs, and Occam is depicted as clean-shaven. There is also precedent in that XP gain is level scaled and there is indirect level scaling for the damage reduction from armor.

What needs to be tested

Uhm, everything, really. :smiley:

  • Pelt a mob that has known SFX values (where to get this?) with various attacks and observe the SFX proc chances.
  • Do this for different attack strength values and for multiple level differences between player character and mob.
  • Test dual wield behaviour for Focus items:
    • Does SFX attack strength follow the 0.6 scaling factor for damage?
    • Does SFX attack strength behave differently for the main hand and off hand focus?
    • Is there a difference when the attack strength mods are in a different focus from the elemental damage mod?
  • Does putting a mod with “adds x% elemental damage” add another proc chance for the SFX when the elemental damage type is the same as the weapon base damage type? If so, does it do this for every such mod that is added?
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Thanks for consolidating this here, also great formatting for readability.

Yup, I’ve since confirmed this. Data-wise, monster ranks/grades affect:

  • Size
  • Money chance and money amount
  • Gear level (defined as a level boost)
  • Health (via multipliers)
  • Possible affixes (grade-bound)

And then as regards other inherents, they have the following in a single field:

  • Interrupt defense
  • Max hp bonus
  • AI sight range
  • AI change defense

So no sight of sfx defenses there.
Maintaining the “data-wise” disclaimer, however, as I can’t 100% guarantee the game doesn’t just choose to mind enemy grades in some obscure way that isn’t spelled out in grade definitions.

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ignite is 3%? isn’t it 5% for most and 3% for Cata bosses? or was ignite damage nerfed for everybody at some point?

if cata bosses do suffer reduced ignite damage - why is it necessary to have bosses that process being ignited differently? is it not possible or acceptable to have higher ignite defence on them? is there something tricky about high sfx defence?

I’m fairly certain it was 5% across the board in stock 2007 HG:L. I dimly remember reading about it getting nerfed to 3%, but that might have been in Global, or only for Cata bosses. My memory isn’t what it used to be (narrator: “It never was.”)

Having higher ignite defense would in theory also lead to less ignite damage over time, but the behaviour would show a different profile depending on relative ignite attack strength, especially at the high end where you reliably or at least semi-reliably ignite things.

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