Oh didn't know there was a range, maybe that can be tested
So that range is only if you unparty?

Arreat summit:

Traveling to the Secret Cow Level
To be able to create the red cow portal leading to the Secret Cow Level your character must first complete the "Eve of Destruction" quest (the final quest in Act V) on the same difficulty setting.

NOTE: The Secret Cow Level holds a hidden quest: killing the Cow King (sometimes referred to as "milking" the Cow King; see why below). There is a slight downside, however: completing this quest disables the Horadric recipe used to create the cow portal, for that character on that difficulty setting. It works as follows:

Suppose the cow portal has been created and someone (henceforth: "Kingslayer") kills the Cow King. By definition the Kingslayer is the character that lands the killing blow on the Cow King (if a mercenary or any other friendly unit delivers the final blow, it counts for the character (s)he/it serves). Be aware that anyone may enter the Secret Cow Level through the cow portal.

We use the following terminology based on quest status:

a) "Pre-opener": a character who has not yet completed the "Eve of Destruction" quest on this difficulty (and thus cannot create the cow portal yet).
"Cow-quester": a character who completed the "Eve of Destruction" quest but not the Cow King quest on this difficulty.
c) "Ex-opener": a character who completed the Cow King quest in a previous game on this difficulty (and thus cannot create the cow portal).

Only characters INSIDE the Secret Cow Level at the very instant when the Cow King is slain can potentially complete the quest. Now,

(1) IF Kingslayer was a or c, THEN everyone is unaffected, i.e. Cow King quest status does not change.
(2) IF Kingslayer was b, THEN every a and b INSIDE at that time permanently loses the ability to create the cow portal on this difficulty setting.

Note that in case 2 even characters who complete the Baal quest afterwards will nonetheless remain unable to create the cow portal. Also note that it makes no difference if you are in a party or not. Location: INSIDE/OUTSIDE at the time of the kill is what matters here.

Because of the above: When in doubt, keep out!

the other pertinent thing is to note that a quest kill of the cow king (which disables the quest for anyone inside the portal at the kill time, allied or not), is easily recognizeable because a quest killed king will drop a crap ton of stamina potions (milk).
non-quest killed kings, ie killed by someone who already had the quest disabled or not finished baal, won't drop the mass stamina potions.

that doesnt explain how the chant bots do it though, they can still make ng no matter who kills king. i would kinda like to know what the chant bots are doing as well.

holy shit, ive played this long and never made that connection.

Is the chant bot in town while the king is killed?
If yes, that's why

yes 100%, ty.

http://classic.battle.net/diablo2exp/quests/cow.shtml

''In addition to the somewhat randomly generated items The Cow King always drops 8 x Stamina Potion (MooOOOooo, MILK!) when killed for the quest. Since these potions are not dropped otherwise, they serve to verify
if it was in fact a quest kill.''

(^the text following the quoted portion from #12)

The entire paragraph was part of the Arreat Summit March 7th, 2011 update:
https://web.archive.org/web/20110310131152/http://classic.battle.net/diablo2exp/
''Cow Level (text changes)''

did you write that by any chance?
I know geoff or micah or whoever was updating the site at the time was just copy/pasting in whatever people emailed him about game mechanics, whether it was right or wrong. I know that because I wrote a few sections of it

This post was edited by Goomshill on Jan 17 2020 02:23pm

When Baal Quest is Done:
- You lose portal when the King dies while your INSIDE the Cow Level.
- You do not lose portal when the King dies while your OUTSIDE the Cow Level.

When Baal Quest is not Done:
- You do not lose portal when the King dies while your INSIDE the Cow Level.
- You do not lose portal when the King dies while your OUTSIDE the Cow Level.
- I completed Baal Quest, You do not lose portal even if you personnaly killed the King prior the Baal Quest.

And:
- Players who have already killed the king can do so again without completing quest for other players in area.