So, it's always been in the back of my mind that the less an NPC dies, the more experience it gives. I've also heard a myth that the more adventurers who die to an NPC, the more experience it gives -- this one, I'm extremely doubtful of. The former, not so skeptical, especially after a bit of hunting I've done recently keeping a very close eye on my experience V.S. what I'm fighting and how many I'm fighting.
I've tried to make the following as thorough and reasonably succinct as I can.
To cut right to it, though, this has begged the question(s):
Is NPC Experience Gain incremental (Denizen Bob gains <X/Z> Experience Output every <Y> time, where Z is the max Experience output)?
Or is it over time (Denizen Susan gains <X> Experience Output every <Y> seconds until having hit <Z>)?
How long does it take for Y to transpire?
When does X become a diminishing return? (Very subjective question, that)
Is Z modified by the strength of the NPC, making stronger NPCs require more Y to fill Z?
If Denizen Bob and Denizen Susan are fought at the same time, by what formula is the increase in Experience figured? (Denizen Bob will normally not attack unless attacked, you strike Denizen Bob and Denizen Susan at the same time. Both attack you, and you kill both)
When does this increase in Experience output slow, if at all? (Denizens Bob, Martha, Susan, Fred, Yankovich, Natalie, Gerald, and Portman all attack you at the same time -- is the amount of experience you're gaining at the same ratio as if Bob and Susan engaged you?)
If you aggravate multiple NPCs normally passive, retreat, then re-engage on only one,(while the other(s) still try to kill you) does the experience modifier still come into play? If you finish killing the whole stack one at a time, while all are hostile and you have re-engaged, does the multiplier still come in to play? Is it reduced by retreat?
If someone has already done research on this, please, please, please point me to the thread.
I don't like long goodbyes.
After a denizen returns from death, experience starts building up after a delay (few hours maybe?)
Bonus experience caps out after 4-6 days.
Cap is between 2 and 3 times their original benefit.
If bonus doesn't cap, then it slows significantly after this point.
Denizen strength has no effect on how much the cap increases, but it takes into account the original amount of experience the denizen would give, so you -are- getting more off stronger mobs accordingly.
Not entirely sure on the bonuses given by stacking mobs, though it seems either insignificant or just blanket applied to all mobs that -do- stack, regardless of whether or not they -are- stacking.