ITS ALL ABOUT FIREBALLS! Gods I had so much fun with it!
Well, if it's all about fireballs, then I will have to go back and rest after each major fight. My Mage only has 2 3rd-level spell slots (and one of those is typically a Haste).
Actually, I suspect that the Web/Entangle is more important for surviving those fights. The Wights come in big numbers, and the level doesn't offer any good choke-points where your front-liners can fight them 2 or 3 at a time. First and foremost, you need to slow the rush. Doing damage is secondary.
Kiting dude!
That said, you do have to rest a bit, and use some other tactics. I don't recall it being the hardest encounter.