There are no "spooky trees" anymore in the present version of HKO in 2011. They have been ingame in the beta of HKO in 2008 though. One of these trees gave out a quest to kill a "cruel" wood-elf. HKO has been changed a lot in the meanwhile, you cannot virtually kill any creatures now anymore, only put them to sleep.
Spooky trees could be found in 2008 on bottom right of South Secret Peak.