So over the years theres been a wide variety of methods and tactics to level quickly and efficiently.

A friend of mine has 4 of those +300% xp elixirs and wants to level a character from 1 to whatever, think they cut off at 85 or 90.

Leveling is the area of the game I am least familiar with and never do it. I don't have a horde of alts as some people do and I despise the leveling process. The few characters I do play were all leveled YEARS ago and I only level them from old cap to new cap each expansion and haven't made a new one in years aside from my MOP monk, which I basically leveled by dungeon tank queue spam until 80ish then questing the rest.

I know getting ran through dungeons with the elixir was a good way to level quickly. I've also heard of people doing something in the molten front to somehow level very very quickly, but I believe that was changed so you cannot do it anymore.

So i'm just wondering what the absolute fastest way to get from 1 to 85-90 would be. I'll be helping her, and she has several of those experience elixirs.