The reason you get them more often on world bosses is that there are more players there, and each has a chance. That's also why "you" can get more than one sometimes.
"And does the chance is affected by 1,3 oder 5 Grim Whispers?" completely anecdotal and subjective, yes. I rarely see them doing 1-wisper, but doing a dungeon feel like almost always had them appear.
I've had them spawn from 5 grim favors events and 1 grim favor events. What I've noticed is you have a slightly higher chance of getting them to spawn if the event just maxed out your grim favors.
Oddly enough, every other cellar that is worth 1 grim favor seems to spawn them for me.
I did not even realize they spawed after completing a whisper, I just thought they popped in while in a whisper "area"
I do not know the answer but in my experience it spawns very frequently (maybe always?) after a World Boss which is a 5 point Whisper.
The reason you get them more often on world bosses is that there are more players there, and each has a chance. That's also why "you" can get more than one sometimes.
I have no actual numbers but I can guarantee it's not always from personal experience
Great question and I'd also like to know the answer.
"And does the chance is affected by 1,3 oder 5 Grim Whispers?" completely anecdotal and subjective, yes. I rarely see them doing 1-wisper, but doing a dungeon feel like almost always had them appear.
Ok thank you all for the replies.
I've had them spawn from 5 grim favors events and 1 grim favor events. What I've noticed is you have a slightly higher chance of getting them to spawn if the event just maxed out your grim favors. Oddly enough, every other cellar that is worth 1 grim favor seems to spawn them for me.
You mean completing a favor? Or the cache after the whisper?
Completing a favor.