I mentioned there was a method in the shoutbox and for future reference, I'll describe it here. In order for this method to work, you need the assistance of at least one level 65 player. Technically anyone 60+ should work, but then they'd probably want to level too and level 65 players would make this faster.
- Go to the Charmer's Caldera dungeon in Shimmersand
- The player being leveled needs to mentor down to 50. If incapable of mentoring down to 50 (requires level 55+ I think), mentor down to the closest you can get. Mentoring down will result in more xp.
- Pop whatever XP potion you have available. It'll speed this up tremendously.
- The level 65 player then proceeds to round up all mobs and kill them. Mobs will do next to no damage to them so there's no danger is rounding up entire areas and spamming AoE.
- The snake guy boss is the last one you fight. The last boss of the dungeon spends a while talking before you can attack, so just skip it and leave the dungeon (run past the final boss).
- The party leader resets the instance (right-clicks their own portrait frame and selects "Reset Instances").
- Repeat until either you're done or the game puts you on timeout from doing too many dungeons too quickly.
We managed to get Buro from 63 to over halfway to 65 in an hour (I think?). We ran into a stranger who wanted to do it too and after we got him to 65, he ran Buro and my mage through using his main for a bit. My mage gained about half a level in a couple runs. This was all without any xp potions, too. No matter what, it was waaaay faster than questing in NT.
Where did I hear about this? This video. Skip to a minute in for the actual info.