Wikia

Wikihack

Yeenoghu

2,032pages on
this wiki
Talk13

Yeenoghu, &, is a monster in NetHack, specifically, one of the demon lords. He can deal out tremendous physical damage, and magic missiles from afar, but is not generally regarded as a problem if you are prepared for him. He is generated with a flail. Yeenoghu respects Elbereth.

Yeenoghu, together with Juiblex, is one of the two demon lords that can be summoned with chaotic own-race sacrifice. He will be peaceful then.

Though you might be prepared for Yeenoghu, you may not be prepared for what he can summon - Demogorgon - who is altogether a much bigger threat, capable of hitting through -20 AC and beyond. Since Yeenoghu has an annoying habit of hitting you and teleporting away, you may want to make him a priority kill, even if he can't hurt you, Demogorgon will.

Combat Edit

Yeenoghu will teleport next to you to attack you and fire magic missiles and then teleport away. He escapes upstairs to regenerate when his hitpoints are low, so an effective strategy would be to camp on the up stairs when he teleports himself off of them. He does respect Elbereth, but be sure you can deal with confusion or have it written already, since you are unlikely to write it correctly while confused.

Do not try to charm Yeenoghu; his high level and magic resistance mean you would waste more turns than in a melee fight. Also, he is covetous, so he would only become peaceful.

History Edit

Yeenoghu first appears in NetHack 3.0.0.

"A ludicrous bug" Edit

Yeenoghu is the subject of one of the longest-running bugs in NetHack history. In NetHack 3.1.0, the Riders were introduced. The code that handles their special attacks comes right after that which handles Yeenoghu's confusion attack[1]. Early versions had this code inserted carelessly; consequently, after Yeenoghu used his confusion attack, execution would proceed into the section that handles Death's touch[2]:

Yeenoghu reaches out with its deadly touch.--More--
Do you want your possessions identified? [yn]

A comment at the end of Yeenoghu's section read:

/* fall through to next case */

and contemporary source-divers thought from this that the behavior was deliberate. Thus for many years the bug was never reported.

Pat Rankin of the DevTeam was made aware of this property in a rec.games.roguelike.nethack discussion, and called it "a ludicrous bug". [3] The then-current version was NetHack 3.3.1. In NetHack 3.4.0, Yeenoghu's illicit deadly touch was taken away.

Umber hulks were not affected, because their confusion attack is handled in a different part of the code.[4]

These source excerpts might make clear the origin of the bug. Here is src/mhitu.c lines 999-1012 from NetHack 3.0.0; the Riders do not yet exist:

#ifdef HARD /* a non-gaze AD_CONF exists only for one of the demons */
            case AD_CONF:
                hitmsg(mtmp,mattk->aatyp);
                if(!mtmp->mcan && !rn2(4) && !mtmp->mspec_used) {
                    mtmp->mspec_used += (dmg + rn2(6));
                    if(Confusion)
                         You("are getting even more confused.");
                    else You("are getting confused.");
                    make_confused(HConfusion + dmg, FALSE);
                }
#endif
                /* fall through to next case */
            default:    dmg = 0;
                        break;

Here is a partial quote of src/mhitu.c lines 1214-1258 from NetHack 3.1.0, the first version to implement the Riders:

            case AD_CONF:
                hitmsg(mtmp, mattk);
                if(!mtmp->mcan && !rn2(4) && !mtmp->mspec_used) {
                    mtmp->mspec_used = mtmp->mspec_used + (dmg + rn2(6));
                    if(Confusion)
                         You("are getting even more confused.");
                    else You("are getting confused.");
                    make_confused(HConfusion + dmg, FALSE);
                }
                /* fall through to next case */
            case AD_DETH:
                pline("%s reaches out with its deadly touch.", Monnam(mtmp));
                [... the rest of the Rider code ...]
            default:    dmg = 0;
                        break;

The Rider code was carelessly placed between the AD_CONF section, which handles Yeenoghu's confusion attack, and the default section, where it was supposed to finish. Thus execution improperly proceeded into Death's touch attack.

The bug was written up as bug C331-96[5] and was fixed in NetHack 3.4.0. Here is src/mhitu.c lines 1474-1486 from NetHack 3.4.3:

            case AD_CONF:
                hitmsg(mtmp, mattk);
                if(!mtmp->mcan && !rn2(4) && !mtmp->mspec_used) {
                    mtmp->mspec_used = mtmp->mspec_used + (dmg + rn2(6));
                    if(Confusion)
                         You("are getting even more confused.");
                    else You("are getting confused.");
                    make_confused(HConfusion + dmg, FALSE);
                }
                dmg = 0;
                break;
            case AD_DETH:
                pline("%s reaches out with its deadly touch.", Monnam(mtmp));
                [... the rest of the Rider code ...]

The "dmg = 0;" and "break;" lines duplicate the ones in the default section, and Yeenoghu is restored to his pre-3.1.0 behavior.

References Edit

  1. mhitu.c#line1474
  2. mhitu.c#line1485
  3. Pat Rankin, "Re: YASQ: Yeenoghu". rec.games.roguelike.nethack, April 9, 2001.
  4. mhitu.c#line1948
  5. www.nethack.org NetHack 3.3.1 bugs

Around Wikia's network

Random Wiki