card:Curse of Death's Hold Is a good sideboard card, but not a mainboard card. I'd put it and the Niv's in your sideboard in for 4 Snapcaster Mage
Not sure why Nephalia Drownyard is included.
Are you trying to mill?
I don't think Forbidden Alchemy fits. I don't see the benefit to put 3/4 cards into your graveyard when you have not so many flashback/reanimate whatever cards. Wouldn't Divination be better, for less?
Olivia Voldaren is a pretty great Grixis coloured card as well.
Hey, i run grixis too and i love it.
some advice:1. Replace Lilianas with Jace, Architect of Thought . It helps you dig for the game winners like Niv, Bolas, and Olivia.