Static Field Bug

[ShadowHM]

I encountered this one in a three player game in Hell last night.

My Sorceress companion used static field on Izual and his life bar shrank to a sliver, instead of the expected half. :o It took very little time to dispatch him after that.

My companion remarked that he had seen this happen before, but was not sure what specifically triggered it, as it did not happen all the time.

I have heard of this before, but only in the context of TCP/IP games set to 'players 8' and I was told that it occurred for only the Act 4 and 5 Super Bosses and only in Hell mode. The theory presented was that their life was boosted so much in such games that it would 'wrap around the numbers'.

Is that what causes it? And if so, why did it happen in a three player game? And why was it only sporadic in the experience of my companion?

[ALnitak]

As far as I know, it depends on the number of players in the party (or simulated players wirh players X command). A friend of mine noticed that with his sorc, in players 4 or 5 IIRC, on Izual but also Mephi. Now as for he origin/explanation (if there is one) of this thing, I don't have a clue.

[Kevin]

Just out of curiosity, what were the classes of the other chars in the game?

I need to run more testing, but I am starting to see a strange trend with any type of elemental damage and the stun effects that a bear can do with either maul or shockwave. It seems that if the stunning hit lands at the same time as an elemental attack, the elemental attack does way more damage than it would normally, as if the damage was calculated with a negative resist or something.

It doesn't seem to happen if the monster is just stunned, but if the stunning attack and the elemental attack hit at the same time. FO and shockwave when hitting things at the same time where killing things in 1 or 2 FO hits when it normally took 4 or 5 FO's and 15+ shockwaves by themselves. It was not just the FO's hitting multiple times either. It was repeated with fireball and glacial spike spells as well. FO was used because it was easier to time the hits to be simultaneous with it. Though with what we tried maul and other spells looked to do it as well.

The tests were also not in controlled conditions, another reason I haven't posted on it before either. But I would be really curious if you were playing with someone who was using a stunning attack.

[Nicodemus Phaulkon]

Just out of curiosity, what were the classes of the other chars in the game?

This "bug" can be reproduced ad nauseam by a solo Static Fielding Sorceress in a Hell game on Players 5 or greater. I've done so several times this morning.

Also, noticed it with my paladin's Schaefer's Hammer on Shenk. By the time he'd pounded his way through the scrambling masses surrounding Shenk's position (and thus setting off several Static Fields), Shenk, untouched save for the SF, was sitting at a sliver of health. One hit brought him down.

*edit: sneezed whilst typing "ad nauseam". *sniff* Pard' me.*

[ShadowHM]

Just out of curiosity, what were the classes of the other chars in the game?

The characters facing Izual were two of the three (third was in Act 1).

They were a bow sorceress (Demon Machine) and me, the Bow Assassin (Pus Spitter). I am not sure what the Shadow Master was doing at the time.

[Ruvanal]

I have heard of this before, but only in the context of TCP/IP games set to 'players 8' and I was told that it occurred for only the Act 4 and 5 Super Bosses and only in Hell mode. The theory presented was that their life was boosted so much in such games that it would 'wrap around the numbers'.

Is that what causes it? And if so, why did it happen in a three player game? And why was it only sporadic in the experience of my companion?

The explanation presented is partially correct. Some of the tests done are of the nature of
If( current_life > max_life*50/100) then allow the Static Field to effect the monster.

In some cases you can get the term max_life*50 to a level such that it flips the sign bit and makes the number negative, before the /100 part of the calculation is applied. Since a positive number is always larger than a negative, you will always be able to apply a Static Field to these monsters.

Small digression here on the internal game data storage. Life (and mana and few others) is stored as a (signed) 4 byte value. The lowest byte is used as a fractional portion of a point of life. This is the level that some fo the continuous damage effects work at like poison. The next upper 23 bits (3 bytes minus the highest bit) are used for the full hit point amount of life. The highest bit is the sign bit or sign flag (0=positive, 1=negative). In hex this max life would be 7f ff ff or 8388607. Go a little above this and you will be setting the sign bit (and having probably a fraction of one hitpoint as the other portion of the variable). The magic point to watch for is when you exceed 8388607 in an intermediate step of a calculation.

Example:
Izual hell HP=98688
3 player game life is boosted by a 300/100 factor.
Izual hell 3-player HP=296064
stepping through the test outlined above
If( current_life > max_life*50/100)
If( current_life > 296064*50/100)
If( current_life > 14803200/100)
We have now exceeded the critical point and the 14803200 is actually being treated as -13754624
If( current_life > -13754624/100)
If( current_life > -137546)
And this will be true for any current_life until Izual is dead.

A similar thing will happen with Valkyrie and Iron Golems life when they are at high skill levels due to the amount of +HP% that is applied to them. The Iron Golems get their +HP% from Golem Mastery and the final amount of +HP% is usually achieved with the effects of Oak Sage and a barbarian Battle Orders yell. But do note that these last two effects are not absolutely required, it is just the easiest way to reach that level with legit items on the realms.