The Rogue poisons quests for Horde and Alliance provide the next opportunity for solid skill gains. The quest is gained at level 20 although it may be too difficult for many players at level 20. The item required to complete this quest is contained inside a locked chest that can be picked repeatedly up to 170. If you've already finished the quest, you can still use the chests to gain skill. The chests don't highlight when you mouse over them, so you have to activate your lockpicking skill first and then click the chest.