Correctly performing this will yield no re-pop times on the Shadowman group you just killed. Unlimited Shadowmen. I completed Lore and Legend Shadowman quest in about a half an hour after I started it and completed the Shadowman Language quest shortly after.
The Shadowman that guard the Obleisk of Lost Souls entrance in various zones. I have confirmed this works in Commonlands and Zek.
Requirements:
The Shadowman group of 2-3 must contain a pet. If there is no pet this will not work.
How it's done:
If you are at level where you can get experience killing shadowmen do the following. Since shadowmen are not linked you can pull each group individually.
Pull the first 2 groups, pet or not, kill them all, making sure you leave a group still not aggro with a pet in it.
Aggro the 3rd group. Kill them all EXCEPT the pet. Once the Shadowmen are dead with the PET STILL AGRO. The person the pet is attacking must run away but DO NOT YELL as I have not confirmed if it changes anything. If there are other group members they can remain behind.
Once the person that has the pet Agro gets out of range where the encounter breaks the pet will instantly POOF.
Result:
Upon pet POOF the shadowman group instantly respawns and one or more of them will contain pets again.
Rinse and Repeat until the other 2 group encounters spawn.
Example of how this can be done at levels where they are grey, say you are trying to complete Lore and Legend Quest and need an update or you want to farm the Directives to get the Language (Did both myself)
Find a Shadowman Group in one of zones with Obleisk entrance.
Kill all Shadowmen leaving any pets agro on yourself.
Once shadowmen are dead. Run away from camp.
Once encounter breaks, same as above, the groups contiaining a pet you did not kill instantly respawn.
Understand the following if it's not already clear: If the group does not contain a pet and you kill the shadowmen they will be on regular repop timer. If group has a pet that you DO NOT KILL when you run away that group will instantly repop and the pet will still be there
Theory
Since the encounter does not break due to pet and causes instant respawn I believe there might be other areas of game where pets are involved that you can run away in similar fashion and get instant repop.
This can be used to farm xp, loot, whatever.
Have Fun!
Just confirmed this also works with Treants in Zek that have the "brittle tender" pets.
Following same process as above you can get instant respawn
9/3 - I realized this morning my damage shield is causing damage to the pet. I believe for this to work the pet must take atleast 5% damage.
I went to CL again this morning 9/03 and it worked every time I did it 5 times in a row. Killed first two groups, killed mobs in 3rd group, my damage shield did damage to pet, ran away, went back instant pop.
I also tested a theory I had about not attacking it directly so I attacked pet directly instead of damage shield hitting and I got same results.
added note: I think this trick also shortens repop time for rest of group because by the time I killed 3rd encounter the other 2 groups had repoped. I'm not sure of repop times on the groups though.
9/04 - Confirmed this still works in both areas for Shadowmen AND confirmed it still works with Treants in Zek. The pet in all instances must take damge, works for me every time. In Zek today I was within site of spawn location and it took about 3-5 seconds from time pet Poofed till I saw repop.
Note: Nazeroth's Post was before I realized pet must take damage for this to work. If premium member, please give it a shot for me and post back here
Thanks.