Checks, Difficulty Classes and Roll Modifiers

Rolls and Checks in the RP

This article details the process used by The Athena System to resolve skill challenges.

The Bottom Line

All rolls in this system will boil down to a few simple steps

1. Determine the Difficulty (Set the DC to how difficult the task is. Do not factor in the character when doing this. Consider only the task at hand)
2. Determine advantage or disadvantage (look at the environment and the context to the task. Is someone helping? is someone hindering? is the environment calm and quiet? or is it loud and noisy?)
3. Determine the modifier to the roll (How good is the character at this task. Are they a master at it? Are they just ok? or are they especially horrible at it?)
4. Determine the Result and the consequences (Did the check pass? did the check fail? What happens now?)

1) Determine the Difficulty (Difficulty Classes)

It’s the game master's job to establish the Difficulty Class for an ability check or a saving throw when a rule or an description doesn’t give you one. Sometimes a game master will even want to change such established DCs. When the game master wishes to do so, the game master thinks of how difficult a task is and then picks the associated DC from the Typical DCs table.

Typical DCs

Task	DC	Task	DC
Very Easy	5	Hard	20
Easy	10	Very Hard	25
Moderate	15	Nearly Impossible	30

The numbers associated with these categories of difficulty are meant to be easy for the game master to keep in their head, so that they don’t have to refer to these rules every time they decide on a DC. Here are some tips for using DC categories during play.


If a game master has decided that an ability check is called for, then most likely the task at hand isn’t a very easy one. Most people can accomplish a DC 5 task with little chance of failure. Unless circumstances are unusual, let characters succeed at such a task without making a check.


The game master should then ask themselves, “Is this task’s difficulty easy, moderate, or hard?” If the only DCs the game master ever uses are 10, 15, and 20, the game will run just fine. Keep in mind that a character with a +0 in the associated ability will succeed at an easy task around 50 percent of the time. A moderate task requires a higher modifier for success, whereas a hard task typically requires a much higher modifier. A big dose of luck with the d20 also doesn’t hurt.


If you find yourself thinking, “This task is especially hard,” you can use a higher DC, but do so with caution and consider the power-level of the characters. A DC 25 task is very hard for weak characters to accomplish, but it becomes more reasonable for mid level characters. A DC 30 check is nearly impossible for most weak characters. A god-level character with a +11 still needs a 19 or 20 on the die roll to succeed at a task of this difficulty.

Remember, in the environment of a roleplay, we are not dealing with specific levels. In the statements above the "power-level" of a character is based on how strong the game master determines a character is at a specific task.

2) Determine Advantage or Disadvantage

Advantage and disadvantage are among the most useful tools in A GM’s toolbox. They reflect temporary circumstances that might affect the chances of a character succeeding or failing at a task. Advantage is also a great way to reward a player who shows exceptional creativity in play.
Characters often gain advantage or disadvantage through the use of special abilities, actions, spells, or other features of their classes or backgrounds. In other cases, the GM decides whether a circumstance influences a roll in one direction or another, and the gm grants advantage or impose disadvantage as a result.


Consider granting advantage when …

• Circumstances not related to a creature’s inherent capabilities provide it with an edge.
• Some aspect of the environment contributes to the character’s chance of success.
• A player shows exceptional creativity or cunning in attempting or describing a task.
• Previous actions (whether taken by the character making the attempt or some other creature) improve the chances of success.

Consider imposing disadvantage when …

• Circumstances hinder success in some way.
• Some aspect of the environment makes success less likely (assuming that aspect doesn’t already impose a penalty to the roll being made).
• An element of the plan or description of an action makes success less likely.

Because advantage and disadvantage cancel each other out, there’s no need to keep track of how many circumstances weigh on both sides.


For example, imagine a wizard is running down a dungeon corridor to escape from a beholder. Around the corner ahead, two ogres lie in wait. Does the wizard hear the ogres readying their ambush? the GM looks at the situation and considers all the factors weighing on it.


The wizard is running, not paying attention to what’s ahead of him. This imposes disadvantage on the wizard’s ability check. However, the ogres are readying a portcullis trap and making a lot of noise with a winch, which could grant the wizard advantage on the check. As a result, the character has neither advantage nor disadvantage on the check, and the gm doesn't need to consider any additional factors. Past encounters with an ogre ambush, the fact that the wizard’s ears are still ringing from the thunderwave spell he cast at the beholder, the overall noise level of the dungeon — none of that matters any more. They all cancel out.

3) Determine Check Modifiers

Skill modifiers are used to reflect a characters skill in a specific check or saving throw. When a character needs to make a saving throw or ability check, the GM should ask the character if they have any skills or abilities that would help or hinder them on the check. Edges and Flaws are particularly impactful on modifiers to skill challenges.
Based on the character's response, the GM adds a positive or negative modifier to the roll to reflect these benefits or detriments. Modifiers cannot be lower than -12 or higher than +12. The table below shows some sample reasons for what modifiers might be used in certain situations. Note that these are only guidelines, a GM should use their own judgement when deciding what modifier to use.
Once the GM has determined the modifier to use, they add the character's ability score to the modifier. For example, if the GM decides to use a +3 as the modifier to a Mind roll and the Character has a -2 in Mind, the final modifier added to the D20 would be a +1.
In short: all rolls can be summarized as:  D20 Roll + GM Assigned Modifier + Character's Ability Score.

Modifier	Uses	Examples	Modifier	Uses	Examples
+0	Used for when a character is neither bad nor good at a skill		+1	positive modifiers are used when a character has skills, abilities, or equipment that is assisting in the roll
-1	negative modifiers are used when a character has traits or circumstances that are negatively impacting their ability to perform the task		+2
-2			+3
-3			+4
-4			+5
-5			+6	modifiers of +6 and higher should only be used when effects are stacking together
-6	modifiers of -6 and lower should only be used when effects are stacking together		+7
-7			+8
-8			+9
-9			+10
-10			+11
-11			+12

3A) Types of rolls

Ability Checks

An ability check is a test to see whether a character succeeds at a task that he or she has decided to attempt. The Ability Checks table summarizes that material for easy reference.
Multiple Ability Checks
Sometimes a character fails an ability check and wants to try again. In some cases, a character is free to do so; the only real cost is the time it takes. With enough attempts and enough time, a character should eventually succeed at the task. To speed things up, assume that a character spending ten times the normal amount of time needed to complete a task automatically succeeds at that task. However, no amount of repeating the check allows a character to turn an impossible task into a successful one.


In other cases, failing an ability check makes it impossible to make the same check to do the same thing again. For example, a rogue might try to trick a town guard into thinking the adventurers are undercover agents of the king. If the rogue loses a contest of Mind against the guard’s Mind, the same lie told again won’t work. The characters can come up with a different way to get past the guard or try the check again against another guard at a different gate. But the GM might decide that the initial failure makes those checks more difficult to pull off.
Contests
A contest is a kind of ability check that matches two creatures against each other. Use a contest if a character attempts something that either directly foils or is directly opposed by another creature’s efforts. In a contest, the ability checks are compared to each other, rather than to a target number.


When the GM calls for a contest, the GM picks the ability that each side must use, deciding whether both sides use the same ability or whether different abilities should counter each other. For example, when a creature tries to hide, it engages in a contest of Dexterity against Wisdom. But if two creatures arm wrestle, or if one creature is holding a door closed against another’s attempt to push it open, both use Strength.


Abilities

Ability	Used for....	Example Uses
Mind	Memory, reason, and perceptiveness	Recall a bit of lore, recognize a clue’s significance, decode an encrypted message,Spot a hidden creature, sense that someone is lying
Strength	Physical force and athleticism	Smash down a door, move a boulder, use a spike to wedge a door shut
Agility	Agility, reflexes, and balance	Sneak past a guard, walk along a narrow ledge, wriggle free from chains
Constitution	Stamina and health	Endure a marathon, grasp hot metal without flinching, win a drinking contest
Soul	willpower, religion, metaphysics, and resilience	contact a deity, sense a metaphysical effect, surpass physical limits

Saving Throws

A saving throw is an instant response to a harmful effect and is almost never done by choice. A save makes the most sense when something bad happens to a character and the character has a chance to avoid that effect. An ability check is something a character actively attempts to accomplish, whereas a saving throw is a split-second response to the activity of someone or something else.

Most of the time, a saving throw comes into play when an effect — such as a spell, monster ability, or trap — calls for it, telling the GM what kind of saving throw is involved and providing a DC for it.


Other times, a situation arises that clearly calls for a saving throw, especially when a character is subjected to a harmful effect that can’t be hedged out by armor or a shield. It’s up to the GM to decide which ability score is involved. The Saving Throws table offers suggestions.

Saving Throws

Ability	Used For...
Strength	Opposing a force that would physically move or bind you
Agility	Dodging out of harm’s way
Constitution	Enduring a disease, poison, or other hazard that saps vitality
Mind	Disbelieving certain illusions and resisting mental assaults that can be refuted with logic, sharp memory, or both
Soul	Resisting effects that charm, frighten, or otherwise assault your willpower; Withstanding effects, such as possession, that would subsume your personality or hurl you to another plane of existence

4) Determine Resolution and Consequences

The GM determines the consequences of attack rolls, ability checks, and saving throws. In most cases, doing so is straightforward. When an attack hits, it deals damage. When a creature fails a saving throw, the creature suffers a harmful effect. When an ability check equals or exceeds the DC, the check succeeds. As a GM, you have a variety of flourishes and approaches you can take when adjudicating success and failure to make things a little less black-and-white.

Success at a Cost

Failure can be tough, but the agony is compounded when a character fails by the barest margin. When a character fails a roll by only 1 or 2, the GM can allow the character to succeed at the cost of a complication or hindrance. Such complications can run along any of the following lines:

• A character manages to get her sword past a hobgoblin’s defenses and turn a near miss into a hit, but the hobgoblin twists its shield and disarms her.
• A character narrowly escapes the full brunt of a fireball but ends up prone.
• A character fails to intimidate a kobold prisoner, but the kobold reveals its secrets anyway while shrieking at the top of its lungs, alerting other nearby monsters.
• A character manages to finish an arduous climb to the top of a cliff despite slipping, only to realize that the rope on which his companions dangle below him is close to breaking.

When the GM introduces costs such as these, try to make them obstacles and setbacks that change the nature of the adventuring situation. In exchange for success, players must consider new ways of facing the challenge.


The GM can also use this technique when a character succeeds on a roll by hitting the DC exactly, complicating marginal success in interesting ways.

Degrees of Failure

Sometimes a failed ability check has different consequences depending on the degree of failure. For example, a character who fails to disarm a trapped chest might accidentally spring the trap if the check fails by 5 or more, whereas a lesser failure means that the trap wasn’t triggered during the botched disarm attempt. Consider adding similar distinctions to other checks. Perhaps a failed Persuasion check means a queen won’t help, whereas a failure of 5 or more means she throws you in the dungeon for your impudence.

Critical Success or Failure

Rolling a 20 or a 1 on an ability check or a saving throw doesn’t normally have any special effect. However, the GM can choose to take such an exceptional roll into account when adjudicating the outcome. It’s up to the GM to determine how this manifests in the game. An easy approach is to increase the impact of the success or failure. For example, rolling a 1 on a failed attempt to pick a lock might break the thieves’ tools being used, and rolling a 20 on a successful Mind (Investigation) check might reveal an extra clue.

Natural 20 and Natural 1

Rolling a 20 on the die Does Not guarantee success. Likewise, rolling a 1 on the die Does Not guarantee failure. It is possible for a modifier on the roll to cause a character to pass or fail in both of these situations. It is up to the game master to judge what happens. This system does not use automatic success or failure.