Nexus Dice Mechanics

From Nexus D20 Wiki

Basic Roll

All rolls are made with a single d20 dice. No other type of dice is used. No rolls are made for damage. This is included in the effect of the attack roll. All rolls are made in the form of:

Attribute modifier + skill modifier + bonuses - penalties + d20

It will be made vs a Difficulty Class (DC). You are looking to be greater than or equal to this number. This is the case for all rolls including attack and defense.

Single Roll

One of the prime rules for creating this system is to make it simple and fast. There is only one roll per action. There are as few rolls as possible made. All rolls are versus a DC and not opposed rolls. This keeps things very simple.

Attack rolls are made against a defense DC. There is no defense roll.

Margin of Success or Failure

Margin of Success (MoS or Margin) is the amount you succeed the roll past the DC. If you roll equal to the DC then there is no MoS. This is most often used in attack rolls. The Margin is added to the base damage because the better controlled your attack is then the more vital a spot you can target. There is no separate damage roll in this system.

The opposite of this is Margin of Failure. This is where you count how much you miss the DC by. This is most commonly used in traps. You take the margin of failure and add it to the base damage.

Threats

Skills have a threat range. This is usually 20 (ie a 'Natural 20') but different actions and weapons can change it. It also changes with your skill rank. Your threat range increases to 19-20 at focused and 18-20 at mastery. Other notations on threat range will list them as +1 or -2 or something like that. This means that you increase the range of numbers that is a critical by that much. So a 19-20 is already a threat of 2 so adding a +1 threat makes it 18-20. If you have a -2 to that threat then it is a 20. Your threat CAN go below 1 but has no effect past that. It just means that there is no critical possible with this roll.

A threat on a roll adds +5 to the total. It does not automatically cause you to succeed. If your total result is not greater then or equal to the target number then you still fail. You might look go at it but you still didn't make it. It is just an impossible roll for you right now.

Impossible Rolls

This is a gritty game system. Just like in life there are things that you just can't do because you don't know enough. This is one of the reasons that threats don't automatically cause you to succeed. Some DCs will be completely out of your reach. This is entirely realistic. If you just have a basic understanding of something then you can't do something that requires focused training. Sometimes you might be able to try anyway if it is within your reach but somethings may require too much background knowledge in order to know which buttons to press. You can't just accidentally do it. There might be a tiny chance of doing it but it is not 5% on a d20!

The GM can tell you that it is something you don't know enough to do or can't reach. Sometimes he may not tell you if you don't stop and try to figure out if it is even possible. You can make a roll to try and figure out more in order to find a way to eventually figure it out but don't assume because you are the star of the game that the GM will let you do it just to move the game along. Your failures are our joy!

If you don't have a feat but you do have the skill then you might be able to do the action anyway with a higher DC and longer action types. Discuss it with the GM.

This means that you may need to do something to change your chances by lowering the DC or increasing your bonuses or getting someone else to do it. You have to think about what you are doing instead of gambling on it.

Botch

Skills have an error range as well as a threat range. The default error range is 1. This means that a 1 on a d20 roll you have taken a Botch. This is worse then a regular failure. It can often cause self injury or inconvenience. A failure can be bad but a botch is much worse.

There are several things that increase your error range such as certain kinds of attacks as well as dealing with explosives and such. So a +1 error raises the error range from 1 to 1-2. Some error ranges are 1-4 or even 1-5. This means that what you are doing is dangerous. Even in case of a botch a 1 is always the worst kind and always involves some kind of serious injury. It is very possible to DIE from a botch!

A botch can also cause you to loose the rest of your turn if you have any actions left. It can cause you to loose initiative as well.

It is important to note that you can't use a Hero Point to negate or reroll a botch unless it is a primary skill! However a well played botch result can possibly earn you a hero point for good roll play. Keep in mind that it is not true that the Hero never fails. They often fail and try again. That is what makes them Heroes. If there was no risk then there would be no tension.

Criticals

If you get 5 or greater margin of success then you gain a Critical. Each skill has a list of Criticals that are available and there are several feats that open up more criticals. Criticals in this game are a result of a great roll by a skilled character instead of just a matter of a dice roll. Higher level characters can possibly get several criticals on the same roll versus a low level target.

A critical could lower the time to do an action, give you a special side effect, allow a stunt, target a hit location, etc. Many of the things that you would normally require a penalty on your roll to achieve you can do with a critical. Basically your character is more on the ball then you are.

The skills have a list of criticals and you can take feats to gain more criticals. You can also use a critical to do a stunt to do a side effect on the attack. This can't be something that does more damage to the target but it can disadvantage the target. You need a feat to gain more damaging criticals. You can use it to ricochet a bullet around before it hits to intimidate those around you. You could use it to cut a rope first or cause a person to move around as a part of the attack in a certain direction. You could cut their clothes off with a sword attack or cause any number of funny things to happen.

The point of criticals is that you have done something so well that you get something extra. If you come up with a really entertaining critical then you may get a social or hero point for it.

Counter

A counter is basically an effect that only goes off if the attacker misses their attack. They are most common in Martial Arts and Melee. If you fail to hit them you may put yourself in a bad position. Some attacks only work as counters such as throws. It requires that someone try and hit them for it to work.

Counters lead to two effects. One is called in Interrupt. This is a counter that actually stops the incoming attack and they don't get to finish it their action.

The other is a Boon. A boon is a sort of Counter Critical. If someone fails in an attack by 5 or more then the defender gets a boon. A common boon is to Interrupt the other character anyway so these two Counter effects often go together. You can push your target over or something amusing for the boon. A botch on the part of the attacker can give you a boon as well. Feats with give you more lethal Boons.

Counters allow even a passive defense system like this a dynamic quality. Plus they are fun!

Setup

A setup is when you use one maneuver to support another maneuver. You get a +2 for each setup maneuver in a chain. The other advantage in a setup is that you can pass any criticals and boons on to the final attack. Each attack in the setup still does their normal effects as well. Feats that can be used as setups are listed in the feat description.

Setups are most often used in Martial Arts and Melee but they are also used in Tactics, Driving, and Piloting.