Instance Boosting
From Dual-Boxing Wiki
Instance Boosting - Using a high level character to run lowbies through instances
Level 13-20 RFC/Orgrimmar Easy boosting for Horde low levels.
Level 16-24 Wailing Caverns Easy boosting for Horde low levels.
Level 17-25 ShadowFang Keep Lots of Mini-bosses, decent loot.
Level 28-44 Scarlet Monestary Start with Library, move up to Armory and end with Cathedral. Make sure to pick up the key from the Library on your alts, so they have it for future runs. Free Fireworks in the armory for your next Ding Party!
Level 42-50 Zul'Farrak Lots of Mini-bosses, a lot of xp from the temple event - totems help a lot for this part. Step out of Hex spell cast range for Shadow Hunters, or your alts will get aggro while you're a frog. Having the hammer to summon Gozrilla is nice, he drops a mail chest piece regularly and gives decent xp, plus there's a quest for killing him and looting his scale. It's fast and easy for a 70 to get the hammer from Hinterlands. The drop quests in ZF are horrid for multi-boxers.
Level 48-60 LBRS Lots of bosses, use the free guide at wow-pro.com for information if you've never been here before. There are TONS of quests for this instance, make sure you get them all. There are locked sections and It will take 3-4 runs to complete the quest chains. Expect to be here a few hours, the place is huge. Completed by: Level 70 protection pally 4x healer/hybrid classes (1-2hrs/level). Also completed by: Level 70 Hunter and 4 Elemental Shaman.
Level 56-61 Scholomance Decent xp, can be time consuming depending on your main's class. Some pieces of tier .5 sets drop in here. Best to run with some sort of healer as an alt. Pulling the casters can be a pain, use silencing shot, curse of tongues or counterspell. If you don't have the key to get in, your main toon can get it fairly easily through a quest chain.
Level 56-61 Stratholme Decent xp, can be time consuming depending on your main's class. Some pieces of tier .5 sets drop in here.
Level 55-60 Hellfire Ramparts Really good XP as part of RAF, and still good without it. 20 mins for a full clear using a level 80 mage to AoE groups.
