Sunday, 26 June 2016

Dungeon Master: When to Roll

Knowing when to make players roll and when not to roll is a skill for a Dungeon Master. The scope of the roll is important as well. Do you roll for every jump when crossing containing a long fall and floating disks? Or do you roll once for the entire trip across? I hope to give my advice in this situation as well as provide my argument for why I like the method I use. I'll need to go into a bit of math: you have been warned. It's also partially a brainstorming of my thoughts on the subject matter.

The Problem with Rolling Too Much

In the example of the floating disks, each jump needs to be accomplished in order to reach the end. However, the odds of reaching the end will be the probability of succeeding all of the jumps multiplied together. This means that if you have a 45% chance of success (roll 10 or higher) and you need to succeed on three jumps, the odds of reaching the other side is just under 10%. These odds can slowly sneak up on you and for that reason you need to be careful when rolling a lot (I've seen this occur quite often for persuasion checks). Even if the odds of success of an individual jump are 80%, there is a 51% chance of succeeding on 3 jumps in row (0.8 * 0.8 * 0.8 * 100 to make it into a percent). This means that if a player does enough trivial tasks in a row, they will eventually most likely fail at least once. Depending on how trivial it is, I would say it isn't even worth the roll.

How to Think About Rolling

I tend to think of an activity that is being performed and thinking about the odds of success. What should the odds of making it across the room be? Let's say we decide on a DC 12 acrobatics (DEX) check. This means that the party member with a modifier of 0 has a 45% chance of success and others most likely a bit more (I'm assuming a level 1 party). If it's supposed to be dangerous, I'd be perfectly fine with those odds.

However, the odds of the entire party of 4 making it across are much worse. For simplicity's sake, let's assume everyone has a modifier of +0 for the roll. This will give us odds of 0.45 * 0.45 * 0.45 * 0.45 for a final of 4% chance of everyone making it across. This would be much better if a DC 12 acrobatics check also let a player that misses the jump to grab the edge and pull themselves up. Doing the math we get 0.45 + (0.55 * 0.45) for a total of 69.75% or roughly 70%. The 0.55 * 0.45 part calculates the odds of failing the jump check but succeeding the check to grab the edge. For four players, we get a final of 24% for everyone to make it across which is much better but still a bit too low. Redoing the calculation using a DC of 10 (55% chance of success) we get (0.55 + (0.45 * 0.55))^4 since each player has 0.55 + (0.45 * 0.55) odds of success, which is about 41% odds of success. This is close to that 45% chance I thought was fine earlier.

The above example is meant to show a few things. Even a change of a couple of points of DC can make a huge difference in the odds, especially when the modifier of the character is low. Having a backup option, such as grabbing the ledge, greatly increases the odds of success as well.

How Big a Task?

I personally would not try to make players roll for every jump. It's a lot of rolling and even one failure means a bad outcome. Instead, I'd base the result on the one roll (a really bad roll means they didn't even land on the first platform though they can try to grab the ledge, really close means they only ruined the final jump, etc.) or just describe it without worrying which jump they missed since they still failed. It's also harder to determine the odds of success for 4 consecutive checks compared to a single roll and as a result easier to accidentally make the room harder than intended (“it's easy, I'll use DC10” results in 9% odds of success).

What Results?

The fall in the previous example has been deliberately left ambiguous. A 10 foot fall (1d10 of damage) is more tolerable than a 100 foot fall (10d10 or 55 average damage) for a level one party. The reason is because the result is a setback and less health in the next combat instead of outright death. It also means that the odds of a character dying from the situation is far lower since they can climb back up and try again (or have a party member drop a rope on the other side and climb up). The odds are bad for EVERYONE to make it across on their first attempt. You could also make the odds much lower and expect that your players will do something else (make a bridge from disk to disk, have someone try to grab the falling characters hand, tie everyone together with rope in case they fall, use a rope to drop to the floor and then have the person who made it across drop a rope, etc.). In this kind of situation, it is typically best if your players realize it is dangerous, failure will result in death (being 100 feet above the ground has that effect) and/or that they realize odds of success are low.

When Players Almost Always Succeed

Don't bother rolling when success is almost guaranteed. A 1 still has a 5% chance of occurring on a d20 which means that even an absurdly low DC has a chance of failing. A reasonable exception to this is if the situation is abnormally stressful, such as in combat, since there is a chance of failure that normally is not present. It can also result in some very funny situation in comedy games. Like all things, consider your group. However, I feel usually it's best to just let the player succeed and move on. It can get annoying quite quickly even in a comedy game.


Be aware of stringing together rolls and needing them all to succeed since the odds of success quickly become low. Don't forget to consider the results of failure and what your players know (it will influence their decisions). If the task is so easy that it'll almost always succeed in normal circumstances, don't roll unless in an abnormally stressful situation such as combat (a situation where failure normally nearly impossible becomes possible).  

Sunday, 19 June 2016

Dungeon Master: Roll Half Health

A bit of randomness helps spice things up and make things different. The Dungeon Master has many tools to incorporate randomness such as rolling health. However, keeping things balanced and fair is important as well. For this reason, I hope to share a little trick I use when rolling health for combat encounters.

Roll Half Health

To add a bit of randomness but to ensure that the combat encounter doesn't become much more difficult, roll for only half of the enemies of the same type (rounding down in the case of odd numbers). Then match up the rolled enemies with unrolled enemies and make the health of the unrolled enemy to be 2 * average health – rolled health. This way, the overall amount of health in the encounter remains the same. However, some creaturs will have more health and some will have less. In the worst case scenario, half will have really low health and half will have really high. The number of enemies rolled for can be reduced if less randomness is desired (if there are 6 kobolds, roll for one and match it with one).


4 kobolds are going to be used (using 5th edition Dungeons & Dragons rules). Rolled 3 and 4. Final health is 3, 4, 7 (2 * 5 – 3 = 7), 6 (2 * 5 – 4 = 6). Average health for a kobold is 5.

Used as Guideline

Even without rolling, the basic idea can be used. If you know you'd like to keep the same amount of health but have one of the NPCs to be weaker than the others, you can decide that one of the kobolds will have 4 health (meaning that another will have 6).  

Sunday, 12 June 2016

Dungeon Master: Long Distance Travel

Travel is part of tabletop role-playing games. In some cases traveling may take quite a while but in others it may take almost no time at all. This refers to both how long it takes to travel in the world of the RPG as well as the real world. However, handling long distance traveling in particular can be tough to handle for a Dungeon Master. For this reason, I'll be offering tips I hope will be helpful.

Glossing Over It

The easiest way to get around the long distance travel is to gloss over it and get to the good parts. In order to make it mean something, however, resources like food and rations will need to still be accounted for. After that, it's very simple. Just go from one source of action to the next. Doing so too often, however, can make traveling long distances meaningless. Easy access to magic transportation can help make this easier. I'd also recommend reading the travel rules in Dungeons & Dragons 5th edition and preparing some house rules if mounts are used (speeds and mounts are a bit oddly written).

Glossing Over Most of It

There will be parts that the Dungeon Master may want to emphasize. This is particularly true for details of the environment or for building atmosphere. It could be pretty routine stop at an inn for the night, but something should make it memorable, special, and ideally it should be related to where the players are going. Keeping in mind some memorable sights, sounds, and rumours is where I tend to start.

Bumps in the Road

Unexpected events can occur as the party travels. Dangers occur along travels, especially when the players are going towards danger. In those cases, being attacked by creatures or being pursued can add something extra. If long distance travel happens often, I find having that special moment every now and then helps keep everyone on their toes and the tension going. One that is worth thinking about is being pursued. It forces the players to compromise between their safety of being ambushed along their way, possibly getting caught, and also trying to maximize their time at the location they are going to before they have to flee. Forcing the players to choose between helping someone while on their way and their main goal can also create some truly heartbreaking moments if used correctly and sparingly (don't overuse this). The bumps should be special, add something or attempt to slow down the players so that negative consequences occur later. Wandering monsters can also be used, but I find it helps to make sure they are not their just for lengthening travel time. Instead, say something about the environment, give players a reason to push until daylight or give players a reason to stop at an inn (or similar safe place) at night.


The players will want to move quickly towards their location. However, is going safely more important than speed? The current travel rules in Dungeons & Dragons 5th edition already give the players some choices about how fast they go through the environment. However, as the Dungeon Master you can give even more choices. Remember, there can be more than one way towards their goal. Each way will have its own risks and rewards and keeping these in mind can help make travel more engaging. Things may also not go as planned once the players choose their path and the players may be forced to alter their course. I've lightly touched on what choices wandering monsters may force in the “Bumps in the Road Section” already. The choices should have some impact on something such as travel time, or story.

Sunday, 5 June 2016

Dungeon Master: Improvising Adventures

I've devoted a lot of time so far to planning. However, there will be times things go off the rails. Some groups prefer more open ended games as well where the focus is on exploration instead of narrative. Some people just find it easier to improvise as they go along. Still, thinking on this topic I've come up with a few things that I hope will be helpful.

Wandering Monster Tables

These guys are very useful. I don't roll on them very much but they are a great source for inspiration. Think of them as representing what threats the local area contains and how frequent they are. If you don't have one, making a quick one before the session is easy and generally beneficial. That way, you know which creates are most likely in the area. You can also easily put something not on the table to mix things up.

Tactical Maps and Dungeon Tiles

It's much easier to use theatre of mind on the fly compared to using a map or dungeon tiles. Still, dungeon tiles and maps can be easily used with some practice. Maps can be simply thrown down on the table and traversed (might want some blank sheets to cover up where players haven't been yet). Dungeon tiles take a bit more time to set up and as such are harder to use on the fly, but you can think of quick designs, design tables for yourself, or use the tables from the Dungeon Master's Guide. Outside of rolling tables, dungeon tiles will require quicker thinking and also more set up time. With some practice, it can make for an enjoyable dungeon delve.

What Kind of Situations?

Dungeon delves are easiest for me to improvise on, especially when you already have a bunch of maps you could run through. More story focused things are harder, but with a bit of practice it can be done. I typically find that focusing on a few characters and having everything fall out from that is easiest for me and also gets the best results (easy to keep in mind at once). Also, don't forget the calm before the storm and mood when improvising. It's was very easy for me to skip on the details when I first started doing serious improvisation. Don't forget the signs, the sounds and other aspects of the environment that help contribute to the theme and feeling.


Not forgetting details is a big pitfall that can happen when improvising for the first time. However, this is also true for combat. The details are important for tactical considerations such as flanking, good archer positions (where archers can keep out of melee), hiding and many others. Maps, again, remedy this a little bit but not completely. Many times, you'll be forced to populate maps with objects as they are empty otherwise. Keeping a little pile of objects for this purpose helps remind me. Generally, it is easier to respond to what players do instead of throwing something brand new their way. As a result, if the players don't know where to go, it can be hard to think of something interesting to throw their way. As you improvise, keep a piece of paper to write down ideas that you can use later in such situations.

It's Not Easy

It's not easy, but it can be very rewarding to think on your feet. It also means you won't be railroading players since there is very little investment into preparation. Getting good at it also helps cut down on preparation time, which can be a plus if you are busy. It's also much better than missing sessions if you can do it well. Good luck to everyone running games this way and I'd love to hear of any other tips people are willing to share.