The `game_event_npcflag` table
This table contains npcflags that are to be added to an NPC when the specified event is active for the creature with the given guid.
Entry of the game event
Description of the fields
The eventEntry that is tied to this npcflag change.
The guid of the creature that you want to change npcflag for.
The npcflags that you want to set. The value specified here is bitwise added to the npcflag already set on the NPC.
So, if you want the creature to be also a quest giver, just put 2 in this column.