The strange behavior of player if NPC can be see but not allowed in default range 100 for dialogue.
The retail behavior of Fairy Mimyu vs standart L2J in quest for strider.
Next one little addon for collect donations, in items. Everyone player can donate all what he want if has necessary items. After completed collect items NPC will be ready for to do the anyone global action. This action can do the everyone player, just press the button for that. Can be uses as funny event for gift for all online player the unique buff, etc.
Special service NPC for changing characters level. Change level available by specified item Id. After changing the level always checks the skill list and adds new skills or deletes skills who not available for this level.