#haemomancy

If someone had telekinetic control over blood, along with the ability to remove certain contaminants (e.g. particulates, viruses, obviously cancerous cells, etc.), what kind of things would they be most useful for?

Hello - I love this question. There are so, so many uses of this power.

What part of the blood do they have control over? Blood is 92% water, mixed in with proteins, glucose, minerals and hormones. It contains various cells - red blood cells, white blood cells and platelets. Assuming they are able to control blood as a whole, these are some of the powers they may be capable of.

Diagnosis - if they can remove contaminants from the blood, they could also measure the levels of various substances in the blood, thus making them a walking laboratory. They could diagnose cancer, haemophilia, infections, sepsis, Covid, COPD, asthma, liver disease, kidney disease, hormone imbalances, sexually transmitted infections, AIDs, menopause, pregnancy - the list is endless. They could even tell if someone is having twins, a molar pregnancy, or a miscarriage (based on the blood level of hCG). Basically anything that could be measured in the blood is now detectable by them.

Treatment - specific blood diseases like haemolytic diseases of the newborn, leukaemia, and haemochromatosis could be cured by the superhero “altering” their blood. If they’re able to remove cancerous cells from the blood they can also prevent cancer metastasis (spread) but may not be able to remove the original cancer as it usually is found in tissues, not blood. They could also improve wound healing after surgery or a fracture by increasing blood flow to the injury, which promotes healing. They could also cure vascular diseases or any diseases cause by poor blood supply such as strokes, transient ischaemic attacks (TIAs), heart attacks, angina, peripheral arterial disease, chronic venous insufficiency, deep vein thrombosis or pulmonary embolisms. It could help with diseases of excess bleeding like haemophilia, heavy menstrual bleeding, nosebleeds, etc. 

Haemodialysis - they can act like a dialysis machine to remove toxins from the blood. This would be lifesaving treatment for people with kidney failure, or who have poisons in their bloodstream like antifreeze, alcohol or paracetamol.

Emergencies - knowing someone's blood type allows quicker blood infusions (although in a true emergency we always give O negative, the universal donor). They could also stop someone from bleeding to death after massive trauma (like a car crash) or childbirth by commanding the blood to not leave their body, or ligating (stopping blood flow) in the arteries, capillaries and veins that are haemorrhaging.

Prevention - knowing the blood type of both parents can prevent their children from developing rhesus disease, which can be fatal.

Offensively - you could kill someone very easily. If you can stop someone from bleeding to death, you can also cause someone to bleed to death. Bleed in the brain (stroke), nosebleed, bleeding in the lung, vomiting blood, coughing up blood, gastrointestinal bleed, peeing blood, vaginal bleeding, or ruptured aneurysm… you can kill someone in minutes. You can also blind them in multiple different ways (amaurosis fugax, central retinal artery occlusion, central retinal vein occlusion, or stopping blood flow to the optic nerve) and then either undo it or leave them permanently blind. You could cause excruciating pain by giving them testicular or ovarian torsion, or preventing blood flow to an area of the body to cause hypoxia. You could make someone permanently infertile by stopping blood flow to their reproductive organs, or stop their legs/arms working temporarily or permanently. This is a deadly superpower.