A quarter of a century ago, I gathered around a table with my middle school friends and made a 20-sided dice roll — my first in a lifetime of Dungeons & Dragons games. Rolling dice is easy, but figuring out the litany of rules in tabletop roleplaying games takes time to master. It would have been a lot easier if I could’ve just watched Dungeon Masters, a new YouTube show made by the creators of D&D, Wizards of the Coast — and it starts airing today, April 22. In recent years, online tabletop RPG shows like Critical Role and Dimension 20…