[Rygar]

OK, I looked into this a bit, some findings...

I should ask, do necros have 'unlimited' FD time? Or will the FD wear off after a certain period of time?

Just looking into FD in general, there a patch message that was not well archived on 1/20/00 implemented this change:

 

*Feign Death and Pets*

After a serious discussion regarding the Necromancer's Feign Death tactic,
as well as reviewing public opinion on the matter, we have implemented a
change. As we would like everyone to understand why we feel this change was
necessary, here is a summary of the issue:

Problem:
Feign death allows you to become an invalid target in all circumstances,
providing offensive tactics that are abusive. For this ability to remain
balanced, the pet should follow the same rules as invisibility. Offensive
tactics used by other classes involve the creature getting a saving throw
verses the effect. Since creatures do NOT get a direct save verses feign
death (as you cast it on yourself), and since you can retry the combat once
you have feigned death, there is very little risk to necromancer himself.
As this tactic involves charming an NPC and turning it against another NPC,
which could be part of the same spawn, it allows for Necromancers to solo
MUCH bigger rooms than any other class could. This situation is well beyond
what would preserve game balance for any other class (soloing the
Bloodthirsty Ghoul room and Ghoul Lord room, for example).

Example:
While there are many examples of how the Necromancer Feign Death tactic is
abusive, one of the most egregious occurs in the Ghoul Lord room of Lower
Guk. The room consists of 2 Bok Ghoul Guards and the Ghoul Lord himself.
Using the current system, a level 50 Necro can easily solo the room at
virtually no risk to himself. The Necro can get into the room quite easily
with Invis To Undead. To clear the room he uses Screaming Terror on one Bok
and Charms the other. When the Ghoul Lord rushes him, he feigns. The Lord
then turns on the charmed Bok and kills it, taking considerable damage
during the fight. The Necromancer waits until the Ghoul Lord returns to its
spawn point. When the necromancer gets back up, he is in no danger of
being attacked due to the way Feign Death works now. He then charms the 2nd
Bok and Feigns again. The fight goes on and the 2nd Bok is killed. When
the Necromancer gets back up he has a VERY wounded Ghoul Lord AND nearly
full mana. The Lord is now an easy kill, and the Necro collects his special
items.

Solution:
Ideally, Feign Death should work like Invisibility, where summoned pets
suicide and the charmed ones break Charm. We do not want, however, to
adversely affect lower level Necromancers to such a large degree. What we
do recognize is the need to prevent higher level Necro's from exploiting key
spawn points. Hence, when you Feign Death, any charmed NPC will immediately
break Charm. However, summoned NPCs (pets) will NOT be affected. While
this still allows the use of the Feign Death tactic with your summoned pet,
it does not imbalance the game and many dungeon spawns to the degree that
charming an NPC does.

It looks like the 2/17/00 patch added this:

*Spell Changes*

- The "Feign Death" spell, when cast by a Necromancer, will now have a fixed
duration. The Necromancer will receive several warnings prior to the spell
wearing off. This change was necessary because some Necromancers found a way
to gain experience through their pet while being AFK for an extended
duration, such as being in bed for the night. Note: This does not affect
Shadowknights or Monks.

I believe the timeout of the FD buff was 15 mins as I found a reference here:

It is obvious to anyone with a brain in their head that it's unbalancing to
have persistent pet with fd. It allows you to kill a mob with zero risk to
yourself. This proposed change is in fact not a nerf but a real enhancement. In
fact, I'm pretty goddamn surprised they didn't just make pets poof when you fd
as if you had cast invisibility.

The previous change (15 minute timeout) *sucked* and made necro fd considerably
less valuable in every way than monk or shadowknight fd.

In that same thread they say they are thinking of removing the FD buff duration in exchange of giving pets a 2 minute suicide timer... I don't know what the 'unintended advantage' was to a 15 minute duration, but makes it seems like the impending change is coming no matter what. Much nerd rage ensues although this seems like a reasonable balance feature in the McQuaid era.

Mention from Abashi was mirrored from station boards here on 02/24/00:

Abashi
"Well, it appears that the "wearing off" effect of Feign Death has had a few
unintended side-effects, by invading aspects of gameplay that the change
wasn't designed to affect. We're willing to remove the wearing-off, if we
kill your pet after a given amount of time (while feigned). We're thinking
of 2 minutes. Thoughts?"

I didn't look too much more into it after that, but seeing as how the patch notes show a removal of this feature, I would hypothesize proper mechanics as follows:
-Up until 1/20/00 FD had zero affect on pets, on that date charmed pets insta break but summoned pets do not die (can remain indefinite). Can also stay FD indefinite
-On 2/17/00 FD for necros only gets a 15 minute duration
-Some undetermned time between 2/18/00 - 6/6/04 FD duration for necros (possibly?) removed and pets are on a 2 min Suicide Timer during FD.

How is FD currently working for necros on P99, unlimited duration?

Edit: Found in era FD guide on Casters Realm mentioning the 2 minute suicide for Necros / SKs:
http://web.archive.org/web/200012180...eign_death.asp

Application

The general application for all three classes with this skill is to avoid dying when in trouble. However the skill has to be used differently by each class, and can have further uses as one becomes a more experienced player. Keep in mind also that a Necromancer or Shadow Knight skeleton pet will suicide after two minutes of its master being feigned, a charmed pet will be instantly released.. Here is a summary below of some of the extra uses for feigning death: