Another, notably shorter cliche I have taken note of an issue with. When writing fantasy roleplaying, not everything needs an explanation. The whole backstory of the world, the events, the mechanics and philosophy of magic, the effects and express details do not need to be stated; implications of it should be. It should not feel like there is a manual being written about them, about how "X magic does Y things, but when it happens to be here it does Z." or the details of every race and the entirety of the history of their people leading up to the current era. The players, unless relevant to their character, do not need a history lesson on every major event that has transpired over the past few hundred years and the minute details working in it. I suspect the reason that this is so common is that in order to make the prospect seem larger and more relevant, Game Masters go through tremendous effort to lay out everything verbatim, in the process destroying much of the mystery. The second reason I suspect this is, is because players have a difficult time grasping just what they wish to do or fleshing it out without delving into the mechanics of it. We, fellow players or readers alike, do not need to know your fireball magic costs three points of mana, burns at this specific temperature, was learned from a college of wizardry and requires the phrase, "Ignatorio!" in an obscure language's specific dialect to be cast. This is an issue of "Show, do not tell." failing to be adhered to. Likewise, a related issue spawns is that every player under the sun seems to want to develop their own intricate system; there is no need for three different forms of wizarding magic, warlock pact magic, sorcerous bloodlines, rune magic specifics, then spheres of magic used by some. All of them are "arcane" and it has become a cliche to try and stuff as many disparate things into it, almost all of them loaned from media, for the sake of appealing to the audience rather than just say, "You tell me how you manage it, I will decide if that seems reasonable or not in the world." Summarized, the cliche of spelling everything out in fantasy and eliminating the mystique and wonder of it is dreadfully overdone.