My Me/N caster beatdown build

This is my Mesmer/Necro build that I've been using lately, and it's pretty deadly. The damage I do to casters is pretty insane!

-Backfire
-Ether Feast
-Shatter Enchantment
-Power Spike
-Wastrel's Worry
-Conjure Phantasm
-Soul Barbs
-Faintheartedness

There are different attributes here, but I can keep them high with runes.

My gameplan with this build is pretty simple. First, I hit them with a Soul Barbs so whenever I hex them they get hit for around 26 damage. Next I hit them with a backfire (hex) so if they try to cast they're toast. After that, I hit them with Wastrel's Worry and Conjure Phantasm which are also hexes. If I were fighting a monk, I would've shattered enchantment pretty quickly. Also, whenever I see them casting I immediatly smack them with a Power Spike for around 70 damage. If they're still alive I smack them with more dots (damage over time). I've found this build to work very well, since the damage with the hexes + dots is very fast. The only problem I have is with energy. I don't know what to replace either Ether Feast or Faintheartedness with for an energy stealer.

Well, can I make this build any better?