I propose a new effect for the "Commune with Nature" spell: rekindling questgivers.
Or whispering back their lives, in a way.
How could that work:
Whenever a questgiver is killed (either a tree or boulder) the immediate area around it (like 1~2 tiles on each direction at most) could keep its spirit so, if a new tree is planted in that area (or if a boulder is carried and placed on it), using the spell Commune with Nature next to it would "bring back" that questgiver.
Also, quests wouldn't fail when a questgiver dies but rather "update" to a halted status showing where the questgiver was exactly, so it's easier to replant/bring back boulders.
I think that would be kind of neat and is part of an effort of coming up with ideas for more persistent/eternal worlds :3