So I’ll admit I’m making a few assumptions here. But. His name is Vilis (vile? Anyone?). He’s a demon. I mean, I don’t actually know what he’s doing with that blood he’s brokering, but…it seems to me like contracts sealed in blood usually don’t favor the person giving away the blood. Also observe that Vilis’s game ability is used to debilitate other creatures. What do you think he’s doing with all that blood?
I feel like this should go without saying, but there’s some seriously nasty stuff that can be passed on through blood-transference. There’s a reason this stuff is heavily regulated. The CDC’s short-list of blood-donation screening tests include Hepatitis B, HepC, HIV I and II, HTLymphotropic Virus I and II, syphilis, West Nile, Zika, Babesia, T. cruzi, and cytomegalovirus, besides general screening for bacterial infections. (For more information on blood safety, check out the CDC here.) I don’t know what cytomegalovirus is, but it sounds like something that could take down a dinosaur (although, according to the Mayo Clinic, it’s actually not that serious for most generally healthy people).
Point is, we have a rogue agent here distributing unregulated blood samples. You know what, Vilis? I’ll tell you what could be mine, if I signed your stupid contract. AIDS.
10,000 Reasons Why the MTG Multiverse is a Terrible Place to Live 