I have one 300% xp elixir I've been saving since MoP and am going to use it on a toon I plan on boosting once it's level 60(with the Legion boost). Where and in what way would be the best to get the most levels out of the elixir? Like what level range should I use it at and what should I get the XP from? I'm talking about what point from level 1-60.