Welcome to the forums Chili!!
First, You need Battle forge. Its a must in this kind of deck, without battle forge you will be spending every round equipping yourself, when you could be attacking.
Take out Sectarus for a extra Lash of Hellfire. You are running nowhere near enough curses to warrant the use of a sectarus over a extra Lash.
Needs more bear strength. One for your mage is a must, one for your big creatures is as well, and you are running quite a few big creatures.
Add elemental cloak. Its not essential, but it helps alot more then you think.
You can have two rings equipped at one time. Fire shaper ring will add to the lash, as well as your attack spells. Get it in there.
Vampirism on a mage is great, Regrowth belt has won me games where I have been 6 damage away from dying, think about adding in regrowth belt.
You HAVE to have some dissolves. (Well, you dont have too, but you are going to need them) Explode is another option that really makes two actions into one, but cost alot of mana.
Death link is an amazing card for a dark mage,
With a mage wand, you might beable to cut down on some incantations, but this is really an option.
You have a good skeleton, but In my opinion, these changes will help you out immensely. Its just deciding on what to cut down on to fit them in that might present a problem. And remember to stay focused. Its so hard in this game to build a book with "tunnel vision" but remember, you are running an aggro deck, keep it aggro.