Energy Drain for Secondary Mesmer?

I believe the spell is called Energy Drain...The spell that steals energy from an opponent.

Anyone know where to get this skill if you're a secondary class Mesmer(N/Me)?

When you reach post-searing, go to Sardelac Sanitarium. Theres a guy called Vassar who has about 3 mesmer quests for you (think you need to complete one to get the last one), but its from one of his quests. Possible the second one you get; sorry but I can't remember what its called.

Energy Tap is from Ambassador Zan and it's an easy quest. Not sure what you have to do first to get the quest triggered, though.