Hi, just some comments from a newbie player...

I would add a dispel, another wand and one more nullify.
Depending on your meta i would evaluate 1 or 2 acid balls

Altar of skull is really too slow, i would replace with idol of pestilence and deathlock. I would take out acolyte too.
Shaggot is really slow and to feed it you need creature with a casting cost similar to the one you use for first attack creatures. Im would take it away.

I would give a try to a spell book with just 1 crystal as mana boost.

Thats all! Let me know if you try it!