Some suggestions:
Spells related to disease, such as contagion
Hold spells
Location and mind-reading spells (using a drop of blood of the target)
Magic jar (taking the form of a bloody cloud that enters the target's mouth and seizes control)
Spells that create emotions in the targets by affecting their metaphorical "hearts", such as friends and emotion
Finger of death (heart explodes or blood boils)
Spells that are symbols or sigils drawn in blood (scarlet snake sigil, explosive blood runes, and so forth)
Neutralize poison and remove paralysis
Cause lycanthropy with a blood ritual (maybe even cause vampirism?)
Summon insect swarm (mosquitoes) and maybe a spell like summon stirges
Transfer youthfulness with a blood ritual
Of course the usual utility spells like detect magic, dispel magic, etc.