Re: Blood mage
As KS suggests, leukemia would best be defined as a long-term drain against CON, STR, and maybe END and PD. People with leukemia also bleed easily and have weakened immune systems, so you might want to do something like link a continuous killing attack that only counters the effects of clotting or resisting disease.
Anemia would be a long-term drain on CON and END much more than on STR. It is another symptom of leukemia, in fact.