The Impossible DC

I hate saying no to players. In fact, saying “yes” has made it into the 4th Edition rules lexicon. Page 28 of the Dungeon Master’s Guide states:

One of the cornerstones of improvisational theater technique is called “Yes, and…” It’s based on the idea that an actor takes whatever the other actor gives and builds on that. That’s your job as well. As often as possible, take what the players give you and build on it. If they do something unexpected, run with it. Take it and weave it back into your story without railroading them into a fixed plotline.

I try to say yes as often as I can. However, sometimes I still feel like I want to say no—and most of the time, this is in answer to the question, “Does my character know about that?”

You see, in a game of Dungeons & Dragons, information is a sort of currency that the players collect and spend to move the adventure forward. Often, a DM wants to limit access to some information in order to drag certain events out a little longer, or perhaps to keep the knowledge limited to certain areas, like an NPC the group needs to speak with or a player that made special pains to include such information in their background.

Almost always I’ll relent, letting the inquisitive player roll against a hard DC. If the player in question spent any effort in focusing on the appropriate skill, even a hard DC will give the player about a 65% chance of succeeding—or more, if he’s clever enough to have other characters assist on the roll.

Worse and worse, I’ve noticed that some players are pretty damn good at optimizing their skills. Even at first level, a player who’s taken the time to pimp out his character can often roll into the high 20’s for skill checks, far surprising the hard column. How can I uphold the precept of saying yes while keeping a tight lock on information that should remain secret?

That’s where the impossible DC comes in. Like easy, moderate, and hard DC’s, the impossible DC is a fourth column for the Difficulty Class by Level table. To succeed at an impossible DC, a player would have had to do everything he could to raise his skill check as high as it could go—and even then, he would only have around a 5% to 10% chance of succeeding.

Of course, this column can be used for any skill, not just knowledge checks. Any time you think that the characters shouldn’t have a chance of succeeding, let them roll again an impossible DC; this allows the DM to say yes and still give the player a chance—however small—of making the impossible, possible.

On last thing: The reason I don’t just set the DC to a natural 20 on a die roll is because then everyone has a 5% of succeeding, whether they’re trained in the skill or not; whether they’ve used magic, feats, or powers to boost a skill or not. I only want players who’ve pumped everything into a skill to have a chance of success—that’s why it’s called impossible!

Difficulty Class by Level

Level Impossible
1 31
2 32
3 33
4 34
5 35
6 35
7 36
8 37
9 38
10 39
11 39
12 40
13 41
14 42
15 43
16 44
17 45
18 46
19 47
20 48
21 48
22 49
23 50
24 51
25 52
26 52
27 53
28 54
29 55
30 56