Question: how do you heat up a fully cooked smoked turkey leg?
Answer: First preheat the oven to 250 degrees Fahrenheit.
Add a dash of water, or broth, to the a baking pan or dish. Amount depends on how many legs! ... 
Place the legs in the pan and cover with foil.
Bake for two hours, rotating the pan in the oven, until you have an internal temp of 155 degrees!