Combine everything in a large pot, slow cooker, crock pot, or the like, and bring to a simmer. Do not boil. Simmer for 30-60 minutes to let the spices blend and permeate everything. It can simmer indefinitely longer; keep a pot hot all evening for refills if you like. Refrigerates and re-heats fine.
Allspice might be a good addition to this too, though I haven't tried it (yet). If serving in a punch bowl for guests, an apple studded with cloves makes a good garnish to float in the bowl with it.