I think
Read the Bones is way better than
Sign in Blood..lets you dig 2 cards deeper...I know its 1 mana more and you don't really have any turn 2 plays, but this is technically an aggro deck and you don't want to be casting a card draw spell on turn 2. You want card draw when you run out of gas later on..it would suck to draw 2 Swamps when you need gas. So howabout a turn 2 creature?
Pain Seer maybe? card draw and 2 power to attack with.
Spiteful Returned? can bestow later on & the ping damage adds up..Sultai Emmisary? The best creature to exploit..acutally nets you power on the board.
Brain Maggot? If you take an early tempo card, it might be far less valuable by the time they get it back. I'm also a huge fan of
Mogis's Marauder in mono black aggro. Kills out of nowhere.
Marshmist titan looks fun. More creatures!!