Add cider to a small or medium saucepan. Place mulling spices in a tea ball and add to cider. Add any optional add-ins.
Heat cider over low heat until it begins to simmer. (Cider does not need to come to a full simmer. Do not bring to a boil.) Remove from heat and allow to steep for at least 5 minutes.
Remove spices (and tea bag, if used). Pour cider into a mug and enjoy.
Notes
Easily multiplied. For larger amounts you may want to use a larger tea ball or a muslin drawstring bag.If desired, spices could be immediately reused for a second batch, but they may be less flavorful. (I do not recommend storing the used spices for use at a later date.)