@Oron Gefen , swanheulen EQ editor works just fine, but there are some things that break quests (not showing up on the list in-game or reverting back to original state). If a quest works fine after editing for solo play, then it works for multiplayer too, but YOU must host the quest, if you don't, then it works with the other person's version. Besides that, you may just be doing something wrong in the editor like cramming too many items in the rewards (if you put too many you will hardly get any more than 5 or so of all the possible ones regardless of what category they are under) and make sure you set the flags right too. Also, NEVER edit supply box contents since it always breaks the quest regardless of what editor you are using, even putting more ammo has made a quest revert to normal for me for example.
