Questions on skills

[MrPurple]

Hey all,

Question on Ether Prodigy.

With Ether Prodigy, when it ends you take 2 dmg for each pt in eng you have.
My question is:
What happens when it is taken away by other means then just letting it die out.
For example, strip enchanment, shatter enchanment, etc.

Also if I cast it again before it runs out, would I still take dmg or would it just refresh itslef.

My next quest is:
Is Mantra of Concentration viable, or more importantly worth a slot?
I am think not so much in PvE, but what about PvP?

I have a Air E/Mes build which has high energy storage and spams using Arcane Echo, Lit Orb and Lit Jav.

Thanks alot.