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Abilities and Skills: an Eternal Rule D20 Developer’s Diary


With the Community playtest approaching, we’re excited to begin sharing what makes Eternal Rule D20 Fantasy such an amazing game. Ability Scores and Skills in ERD20 will be very familiar to anyone who has played a D20-based roleplaying game, and while future articles will showcase the truly unique and mindblowing aspects of this game, Ability Scores and Skills are fundamental principles, and they are the perfect subject to begin our series with.

As the developer, I dug deep into not only what I wanted out of a fantasy roleplaying game, but what would be most appealing to tabletop gamers of all varieties. I began to think back to every edition of all of the roleplaying fantasy classics I have played over my time as a roleplaying gamer, going all the way back to Advanced Dungeons & Dragons. What were all of the barriers that I faced coming into fantasy roleplaying, from a learning and comprehension standpoint? Why were they such hurdles? Do they still exist in the modern editions, and if so, why do they persist?

One of the most longstanding issues many people have is with Ability Scores and in what circumstances each one is best used. Typically, the d20 fantasy games that owe their genesis to the classic Dungeons & Dragons have six Ability Scores used to define a character’s raw performance capabilities: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. The shortcoming of these scores is that they don’t really encapsulate the holistic view of the creatures they are trying to represent, and a few of them are needlessly confusing given the roles they are intended to serve. Dexterity implies a rating for fine motors skills and deftness of the hand, yet a large portion of its use is for coordination and physical agility. In modern editions of Dungeons & Dragons, Charisma is used to rate a character’s charm, likeability, attractiveness, and overall social skill. Yet Warlocks use Charisma to cast spells, meaning players and Dungeon Masters have to logically reconcile an odious, chaotic evil goblin Warlock’s above-average Charisma, while still being a hideous and generally repugnant creature, even among its own kind. That’s not to say that D&D isn’t a great game. Frankly, it’s an amazing feat of imagination and creativity, deserving of all of the praise and respect it’s due. But at the end of the day, the rules that Gary Gygax and Dave Arneson first put together were inspired by the naval and medieval wargames they had previously worked on and had little thought for non-combat aspects of roleplaying. Besides some streamlining, those core rules have changed very little over forty years.

Ability Scores in ERD20

While not specifically delineated as such, the six classic Ability Scores can be broken up into two categories: physical and mental. ERD20 also uses six Ability scores but places greater emphasis on the difference between these two categories and attempts to clearly delineate the roles each score governs. The physical Ability Scores in ERD20 are Strength, Grace, and Constitution, while the mental scores are Intelligence, Wits, and Willpower. ERD20 also continues to break down both mental and physical scores into three further categories which have no specific rules purpose, but rather are categorized as such for the sole purposes of player comprehension and helping players intuitively understand which Ability Score is most appropriate in which circumstances.

The Assertive Ability Scores

Strength and Intelligence are considered the assertive scores. Assertive scores are typically used when a character is directly dealing with creatures, objects, and environments in a straightforward and direct manner. In the case of Strength, this might include lifting heavy objects, climbing high walls, kicking a door in, or kicking a goblin’s head in, among other creatures. In the case of Intelligence, this might include orchestrating a coup, casting certain types of spells, deciphering a code, or crafting a withering social critique that reduces someone to a weeping wreck.

The Subtle Ability Scores

Grace and Wits are the subtle scores. Subtle scores are typically used when a character is indirectly attempting to influence or affect the creatures, objects, and environments they come into contact with or to deal with them in a nuanced manner. The subtle scores can also be thought of as reactive Ability Scores, as they are often used by characters in response to the events unfolding around them. Grace, for instance, might be used to walk across a tightrope, catch an arrow out of the air, parry an attack, throw an object, use a ranged weapon, or backflip off of a wall. Wits on the other hand might be used to undermine someone in their presence without their realizing it, to pen a moving poem or song, to craft a scathing rejoinder to a social barb, or to comprehend another’s motivations and plans.

The Resistant Scores

Constitution and Willpower are the resistant scores. They represent a character’s ability to withstand the effects of the world around them. Constitution might be used to endure a forced walk through the desert, to survive the effects of poisons, to fight off disease, or shrug off physical traumas. Willpower might be used to resist temptations, maintain consciousness despite traumas, keep a hold on one’s sanity, concentrate despite pain or distraction, or cast certain types of spells. The resistant scores also have the added bonus of providing the baselines for a character’s mental and physical health, which we’ll cover in a future article.

Ability Modifiers

Like classical d20 fantasy, each Ability Score provides an Ability Modifier which is added to dice rolls when characters are attempting to determine the success or failure of a given action. Unlike classical d20 fantasy, though, ERD20 determines these Ability Modifiers in a more straightforward manner: an Ability Score’s dice modifier is found by subtracting 10 from that Ability Score. Therefore a character with a Strength of 14 would add +4 to Strength-based rolls, while a character with a Strength of 8 would subtract 2 from those rolls instead. This also means that while Ability Scores in other d20 games typically cap out at 18 for most human-like creatures, ERD20 treats scores of 15 as the high end of that spectrum.

What does that all mean? Well, simply put, it translates into a quick, clean, and simple approach to not only understanding which Ability Scores are most appropriate for a creature to use in order to resolve a given conflict, but also determining the modifiers to those rolls on the fly. It also helps put boundaries on the scale of a creature’s health, as you’ll see in a future article on combat, which prevents keeping track of a character’s wellbeing from becoming a bookkeeping chore.


Skills that provide an additional modifier to dice rolls are a common concept in roleplaying games. ERD20’s approach uses Skill Ranks to represent a character’s training and expertise across a variety of subjects. Unlike some roleplaying games, characters in ERD20 are not restricted from learning any of the Skills available, though certain choices made during character creation can make acquiring some Skills more costly than others. As long as the Games Master running the game agrees that it suits the narrative, characters are free to choose any Skills they wish.

When a character acquires a Skill, they begin at a Skill Rank of 1. As characters develop their Skills this rank is increased. When players are called upon to perform an Ability Check to determine the success or failure of a given action, not only is the Ability Modifier of the Ability Score being used added to the roll, but so is the Skill Rank of a supplemental skill. For instance, a character attempting to determine the worth of an ancient text might be called upon to use their Intelligence of 12 for an Ability Modifier of +2, adding their Appraisal Skill, which has a Skill Rank of 3, for a grand total of +5 to their Ability Check.

Skill Ranks are not directly tied to your character’s level, so as your character gains Experience Points, it is up to you as a player to determine how much focus to place on certain Skills. Acquiring and spending Experience Points in ERD20 is really fun, simple, and intuitive, but we’ll cover that in a future article.

Like Ability Scores, Skills are segmented into categories. For Skills, we have four categories: Athletic, Social, Knowledge, and Instinct. Each category has eight Skills to choose from, for a comprehensive, but manageable total of 32 Skills for your characters to choose from.

Athletic Skills cover how well developed a character’s mastery over their body is and well they can put that body to use. The Athletic Skills are Acrobatics, Accuracy, Brawling, Endurance, Melee, Dexterity, and Poise.

Social Skills cover how well a character can interact with other sentient creatures as well as their understanding and utilization of social norms and customs. The Social Skills are Bravado, Deception, Fellowship, Etiquette, Rites, Performance, Manipulation, and Negotiation.

Knowledge Skills are those that require an understanding of categorization, composition, comprehension, research, and foresight. The Knowledge Skills are Appraisal, Mechanisms, Cooking, Nature, Medicine, Comprehension, Logistics, and History. At the Games Master’s discretion, specific Knowledge specializations may also be taken as their own unique Skills, to represent specialization in the myriad and endless fields of study available.

Instinct skills are those that are innate, uncanny, intuitive, or otherwise incredibly difficult to teach and learn by traditional or even direct methods, often tied directly to the primal nature of the beings that practice them. The Instinct Skills are Reflexes, Stealth, Intuition, Resolve, Awareness, Ferocity, Focus, and Empathy.

Flexible and Adaptable Application

Skills in ERD20 aren’t tied to a specific Ability Score. Rather, they are adaptable and can be used in conjunction with any Ability Score as needed. Does your character need to run across the tops of a series of wooden poles over a pool of piranhas? Grace plus Acrobatics. Climb up a cliff face? Strength plus Acrobatics. Write a textbook on Acrobatics? Intelligence plus Acrobatics. Defend that textbook in a debate? How about Wits plus Acrobatics, or maybe Wits plus Performance to play to the crowd? Whatever tack you want to take, the flexible nature of pairing an assertive, subtle, or resistant Ability Score with a Skill offers endless variety and prevents characters from being shoe-horned into using the same approach time and again.

I hope this article has begun to whet your appetite for what else we have in store, and believe me when I say this is just the prologue to the really juicy stuff. Next time, we’ll be covering two unique concepts that allow for massive amounts of freedom for the players, and sweet, sweet chaos for the Games Master to throw at them: Stress and Reckonings.