These are the way.
EDIT: A little more explanation:
Re-spawn times can be modified in two places:
- DB "world.creature.spawntimesecs" (only for that single GUID of the creature)
- worldserver.conf file "Corpse.Decay.[rank]" (for ALL creatures of the same rank)
The default "spawntimesecs" for all spawned creatures is 300 seconds (5 minutes).
Using ".npc add" command to spawn a "Normal" NPC, for example, will give it a default respawn time of 6 minutes; i.e., spawntimesecs + Corpse.Decay.NORMAL (default value equals 60 or 1min).
The creature must decay first before it can re-spawn. For this reason, the Corpse.Decay.[rank] time of the creature is also its
minimum re-spawn time, since setting the creature's creature.spawntimesecs=0 will remove the default re-spawn time. Therefore, setting a Normal NPC's spawntimesecs=0 means the creature's re-spawn time decreases from 6 minutes to 60 seconds (i.e., applying
only the corpse.decay.[rank] default).
What this all boils down to is simple: increasing the Corpse.Decay.[rank] value means longer re-spawn rates. As I've said, I have mine currently set for 2 hours. My decay rate, therefore, is actually 2 hours 5 minutes (since I've not modified my DB).
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The worldserver.conf parameter, Rate.Corpse.Decay.Looted, affects the decay rate AFTER the corpse has been looted. I have mine set to 0.1 and I would suggest you do the same. I haven't figured out this parameter completely, but I can confirm that setting its value too high, say 9, will cause some creatures, not all, to re-spawn immediately after being looted.
My initial aspiration was to have long re-spawn times with immediate decay after looting, like when skinning, but, after maintaining a high re-spawn rate for many weeks now (I initially set it for one hour but that wasn't long enough for me) I find I greatly prefer having the looted corpses remain. It gives a wonderful feeling of satisfaction after decimating an area
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Personally, I think increasing the re-spawn rate not only allows for a more plotted, more deliberate style of combat execution (for single players), but I also find it, more than any other single modification, redefines the game world into feeling more like a single player game, rather than a MMO.
One caution: a high re-spawn rate may not be acceptable for multi-players because there may not be enough mobs to acquire quest objectives. In fact, I myself had to re-spawn mobs (twice) using the GM command because I didn't get what I needed and there were no mobs left alive, lol. For me, this is a small concern for something that otherwise grants me much greater enjoyment.