Best way to use elixir of Ancient Knowledge

I went from 57 to 75 with 1 Elixir of Ancient Knowledge today and couldn't find any posts about this method so i figured I'd share.

What you need is an Elixir of Ancient Knowledge and either a second account or a nice friend.
Basically the point is the buff does not drain the time when you logout.

Get your leveling character to the outside of an instance that your friend or 2nd account can pull the entire place in 1 pull, but also near your level.

For example from 57-64 I did ramparts. 67-74 i did utgarde.

Now you either go inside or wait outside until your buddy pulls the entire instance and is standing close enough to the entrance that you will get exp from walking in or logging on.

Then log in and tell him to kill them all, should take like 30 seconds or less to down the group.
Go out of the instance and log out, friend resets, rinse and repeat.

I can explain in more detail if people don't understand or want tips.