The final mod that starts in the earlygame, although it is technically on the boundary with midgame.

To start with Blood Magic, you will need a Blood Altar. For this you will need quite a bit of progression in Witchery, and some progression in ChromatiCraft and Aura Cascade.
Once you have made the Blood Altar, and have made the Infusion Altar, congratulations! You have now officialy reached the midgame.