Dice, a map, and notes.I'd be curious to see people tell me what their game space thoughts are for when they run D&D as a DM:
What are your must haves?
Joke: Players.What are the things you have, don't really need, but sure enjoy having?
A better printer for big, full-color maps. Better cartographer software. Physical copies of Stars Without Number and Worlds Without Number. Real pie-in-the-sky time, all my Al-Qadim, Dark Sun, Mystara/Known World, Ravenloft, and Spelljammer books that have...wandered off...over the years.What are the things you wish you had, but don't?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.