The ability to manipulate matter at the subatomic level, with explicit accuracy and knowledge.
From there, I'd be able to pretty much solve any problem.
Enemy? Turn them to goo. Or brain hemorrhage. Or invert their genitals. Explosive toenails. Literally shit for brains. Boobs on the head.
Sick? Convert the virus to vitamins or something.
Hungry? Food.
Solve pollution.
Aging? Reverse oxidants etc...
If it's not from the sweeping fields of Russia, it's only sparkling gulag.