Hear me out... lymph. Less generic than blood and... other things. The lymphatic system is less discussed than other circulatory systems like cardiovascular or excretion, but it is especially crucial to your body's immune defense mechanisms. Lymph is the fluid that flows through your lymph vessels and nodes. It transports white blood cells to different tissues to kill pathogens, and it removes waste and cellular debris. It's especially important in maintaining homeostasis within your body, particularly fluid balance. Also, cancer cells often transport through lymphatic vessels to other organs, so surgeons often cut out lymph nodes to detect any different cell types that should not be there to confirm metastasis.
Imagine an ability user that can manipulate lymph. Maybe solidify it into a blade, either within the enemy's body to stab them from inside-out, or extract their own lymph through pores and create a weapon. Or, the wielder can build up uncontrollable mitosis within the enemy's body and grow massive tumors so big that the enemy gets torn apart. The wielder can also mess with pathogens, maybe from a cold/disease they've gotten themselves, concentrate those pathogens or the WBCs that phagocytized the pathogens, and inject into the enemy's body so it triggers a massive immune response and burns the enemy from the inside.
(sorry I finally had the chance to put my biology degree to use let me ramble a bit)
Is making me vomit a superpower?
