Over time, characters may improve their abilities and characteristics, through experience, practice, and training.
Most abilities—runes, passions, and skills—can be improved by use. When the GM judges that the ability was called upon in a significant way, whether successful or not, the character is granted an experience check for it. The intention is to reward players for using low abilities and risking failure, but calling for rolls in situations where they do not matter (there are no meaningful consequences to success or failure) is not rewarded.
Some Knowledge skills (mainly Lores) cannot be improved this way, as they represent previously accumulated knowledge rather than applied skill.
Experience checks are resolved either at the end of a season (the 8-week periods that a Gloranthan year is divided into) or at the end of a session of play, whichever comes first.
For each experience check, roll 1D100. For skills, add the skill category modifier to the roll. If the unmodified roll is 96–00, or the total is over the ability rating, the ability increases by 1D6+1% (or 4%, at the player's option). Otherwise, it increases by 1%.
Passions are a special case. If a character resists (successfully or not) or ignores a passion (possibly enduring some penalty), the passion gets a "negative check." This is resolved in the opposite way: if the 1D100 roll is 01–05 or under the passion's rating, the passion is reduced by 1D6+1% (or 4%); otherwise, it is reduced by 1%.
The GM may also grant regular experience checks for passions when a character voluntarily follows them in some important or costly way.
At the GM's option, runes may also receive negative checks when their influence on a character's behavior is resisted.
When a character wins an opposed POW vs. POW test as part of casting a battle magic spell (i.e. overcomes the target's resistance), they get a POW check. POW checks are also gained up to once per season, and at sacred time, for taking part in cult seasonal holy days.
POW checks are resolved at the same times as other experience checks. Roll 1D100 under ([species maximum POW] - [current POW]) ×5%. On a success, POW increases by 1D3 points, up to the character's species maximum.
Dedicated and Master members of cults gain a 20% advantage to this roll (increase the target percentage by 20, or reduce the roll by 20).
In addition to experience checks earned during play, characters get to assign and resolve 8 experience checks at the end of each season. Half of these checks (that is, 4) can instead be assigned to try to increase one characteristic (other than POW); see below. These checks can be assigned to any skill, including those that cannot be increased by experience. No ability can receive more than one of these checks each season.
These checks can be assigned to skills with a 00 rating to learn them, subject to the GM's judgement; generally, a teacher is required to learn a new skill, and some are exclusive to certain cults. When the skills is learned, the skill category modifier is added to it. (The category modifier can take the rating below 00, indicating the character needs longer to learn it.)
Languages: If a character has a rating of less than 50% in Speak Language for the local language, they gain a free check in it each season.
Characteristics other than POW can only be increased by seasonal experience, representing training and practice. The roll is the same as for POW gain rolls: 1D100 under ([species maximum] - [current characteristic]) ×5%. On a success, the characteristic increases by 1 point, up to the character's species maximum.
CHA: Charisma can also be increased by +1 for reaching Dedicated and Master member status in a cult (once for each per character), and by great successes and heroic deeds, subject to the GM's judgement.
Skills can benefit from training. A character who has regular access to a trainer (with a rating of 90+%) for at least half a season automatically succeeds at resolving experience checks for one specific skill, increasing it by 1D6+1% (or 4%). Skills at or above 90% cannot benefit from training.
Non-player characters may, at the GM's discretion, receive seasonal experience. Alternatively, the GM may increase their abilities by 100% each year (up to 10% to any one ability; spend 10% to try to increase a characteristic) and give them 5 POW gain rolls.