Checks

Iron & Aether has two types of checks: skill checks and ability checks. Both work very similarly, with the main difference being when they are called for. Each is described in detail here.

Skill Checks. Skill checks are made whenever a character or creature is attempting to perform an action that is not an attack that directly corresponds to an Action, Tool, or Weapon Skill. To make a skill check, simply roll the same number of d10s as your proficiency in the skill, then add the appropriate Ability Score; if the result is > the Difficulty Rating, or DR, of the check, then you succeed! If your proficiency with a skill is 0, then just roll 1d6 and add the appropriate score. Most of the time, Action Skills will use the associated Ability Score, but there are times when the GM might require you to use a different score. In these instances, you still roll the appropriate number of d10s, however instead of adding the associated score, you instead add the score specified by the GM. With Tool Skills, the GM must always specify which score they want you to add, since Tool Skills are not inherently associated with any Ability Scores. Weapon Skill checks, much like attacks, will almost always use STR or DEX depending on the circumstances and the nature of the weapon.

Ability Checks. Ability checks are very similar to skill checks, except that they are called for whenever the action being formed does not directly relate or correspond to any skill. To make an ability check, roll a number of d10s equal to the Ability Score (plus a d6 if the ability is halfway between two numbers) and add the score itself.

(Double) Advantage and Disadvantage

Whenever the term advantage is used, it means that by some stroke of luck or fortunate circumstance, a character has gotten a particularly strong hit against an opponent or has some sort of situational expertise with the skill they are performing or the tools they are using. Mechanically, this means that half (rounded up) of the dice the player must roll are automatically taken at their highest value. Double advantage is when all of the dice the player would roll are automatically taken at their highest value.

For example, say that Sandor the Warrior, who has 3 proficiency with Polearm weapons, decides to strike an unconscious enemy with his halberd. Normally, Sandor would roll 3d6 + his STR score to determine the damage he deals; however, because attacks against unconscious enemies have advantage, he instead rolls 1d6 + 12 + his STR.

Disadvantage is very similar conceptually, except that half (rounded up) of the dice to be rolled are automatically taken at their lowest value (typically 1); similarly, double disadvantage means that all of the dice to be rolled are taken at their lowest value. To extend on the previous example, this would mean that with disadvantage, Sandor would instead deal 1d6 + 2 + his STR score damage.

Should a character gain advantage or disadvantage from more than one source, then they are considered to have double advantage or disadvantage. Additionally, a single source of either cancels out a single source of the other - so for example, if a character gains advantage on something from 2 different sources, then they have double advantage on whatever they are doing; if something were to grant them disadvantage on what they're doing, then their double advantage is demoted to regular advantage.

The Spectrum of Success

Instead of having success or failure be a binary, Iron & Aether assumes that for any given task, there are multiple degrees of success or failure, ranging from Critical Success to Critical Failure. Here is a brief explanation of the full spectrum of success:

• Critical Success (CS). The checking creature succeeds on the check by a factor of 1.5x the DR; they perform whatever they are attempting to do in an exceptional and incredibly skilled manner. Their incredible luck may bestow some boon upon them or another, such as making them temporarily immune to whatever they were saving against or making up for the failure of another creature attempting the same task.
• Success (Su). The checking creature succeeds on the check by meeting or surpassing the DR by a relatively small factor; they perform the attempted task adequately but not amazingly.
• Partial Success (PS). The checking creature fails the check by a relatively small amount, typically reaching about 90% of the stated DR; they may make progress towards their goal without explicitly succeeding, possibly granting them the opportunity to make another check to make progress towards their goal. Alternatively, they may barely meet their goal in an unflattering or unspectacular manner, or after a long passage of time.
• Failure (Fa). The checking creature outright fails the check and does not meet or make noteworthy progress towards their goal.
• Critical Failure (CF). The checking creature does not meet even half the DR of the check, failing to meet their goal and possibly humiliating themselves in the attempt or even making the thing they are trying to do harder.

Throughout the Rulebook, generally only Successes, Partial Successes, and Failures will be explained for a given check, with the results of Critical Success/Failure being up to the GM's discretion.

Check Difficulty. Presented here are two tables that should give an idea of the relative difficulty of various tasks. GMs can use either table at their discretion: the left gives a list of static difficulties that can be referenced quickly and easily, while the right outlines how to calculate dynamic DRs given a task's difficulty.

Deciding When a Roll Is(n't) Needed

As Ability Scores (and skill proficiencies) become higher and higher, the need to roll for certain activities - Very Easy and Easy ones in particular - becomes lesser and lesser. If a character with a high enough Ability Score or skill proficiency is attempting a relatively easy task, then there is no need to call for a roll, and it can just be assumed that the character is able to perform the task. For example, if a character with 5 STR tries to break a somewhat thick piece of wood (DR 10), then it can be safely assumed that they are able to do this quite easily, and there is no need to ask the player to roll on behalf of their character. This has the dual benefit of both keeping the game moving, and rewarding the character for specializing in a given ability/skill to such a degree.

Contrarily, if there is no possible way for a character to succeed at a task given their current Ability Score/proficiency, then there is no reason to make them roll, and you can simply say that if the character tries, there is no way for them to succeed. As an example, if a character with 1 proficiency in Lore wanted to see if they knew an extremely obscure piece of information (DR 40), there is simply no way for them to succeed on that check, so it would be pointless to ask for a roll. Whether or not the character would realize they aren't skilled enough to attempt something would largely depend on their INT/WIS score.