This will be another quick one, I’m still with family. These thoughts are brought to you by an excellent post on hexcrawls I read a while ago… one I’ve unfortunately forgotten and thus cannot cite here.
In RPG systems where the storyteller must roll dice, there’s a long tradition of storytellers hiding the results of their rolls. There are plenty of reasons for this (fostering tension, keeping secrets, the fact that sometimes characters don’t know whether they’ve succeeded, etc.), and some of them are useful. But it’s worth noting that not every roll needs to be hidden. This especially applies to combat in D&D.
I’d argue that—whenever possible—not hiding your rolls is the better course. There’s more to this: when you don’t hide rolls, it’s okay to not hide foes’ stats. You needn’t reveal them immediately, but as PCs spend a while fighting an NPC they will slowly get a feel for the NPC’s capabilities, and that is perfectly natural. This also speeds up play, as you needn’t try to reference material while keeping it secret from players.
With this approach, there are still times when hiding your rolls is better for the feel of the story. For example, hiding your rolls works well when the PCs are surprised or don’t know what they face. This experience of information asymmetry matches the experience of the PCs. In fact, when players are used to getting information about their foes, the sudden lack of information might completely change their assessment of a situation (likely for the worse).
Note that when you’re not hiding your rolls, you aren’t able to fudge them for or against the PCs. Some players love this, some hate it… and it’s definitely more dangerous to the PCs, as dice are random and capricious. Simply put, when not hiding rolls it’s harder for you to protect your PCs from your own mistakes in creating challenges without foreshadowing them sufficiently.
When you’re not hiding rolls, I would suggest playing more openly in all ways; talk with players about what the PCs are able to see, what they might guess based on their previous experience, and what capabilities they know their opponents have (thus far). Be generous with that information! Nobody likes to be “gotcha’d,” and there’s no need for you to trick players in that way. Save that cleverness for creating exciting and tricky encounters, puzzles, or what-have-you.
Of course, all these suggestions cultivate a particular flavor of game. You needn’t use them if you don’t like them. But I’ve had good experience with them, and I think my players felt more rewarded by their victories when they knew that I hadn’t coddled them by fudging die rolls in their favor. I hope you find them useful.