Evidence [v1.16b Xmas] suggests that it takes roughly 1425 experience to advance a skill one rank at 100% potential and roughly 50 Learning. Potentials can generally be considered a percentile multiplier of incoming experience, but the exact mechanics are unknown.
For the mathematically minded or masochistic, you can get a slightly more accurate number using 23/33500 as the normalizing factor equal to the skill gain from 1 incoming point of experience.
Potentials, regardless of whether they are for skills, attributes, or anything else, decrease as you gain levels in those skills, attributes, or anything else.
The formula is: Current Potential = Old Potential * 9 / 10
In Elona+, Current Potential will be between 0.6 and 0.8 of Old Potential, with a sharper decrease at higher initial potential values (more detail).
This game uses integer math for most everything, so all fractions round down.
Also note that if skills or attributes go down, (such as through getting unlucky when drinking from a well,) your potentials can be "refunded" to a degree, as well.
All potentials have a minimum value of 1%, and maximum of 400%.
The function of potential is to serve as a road-block to heavy "grinding" of a skill - rather than sitting in one place, constantly casting minor healing spells or holding up your shield while a rat gnaws on it, the way that some train-through-use games implicitly encourage players to do, potential means that players are encouraged to chase after platinum to train their skills faster, since working to keep potential up by completing (presumably) more entertaining quests or plundering dungeons inevitably becomes a faster means of leveling a skill than repeated skill-grinding.
Skill potential can be raised by:
- Training with a trainer via spending platinum coins. You gain 15% potential - 1% potential for every 15% you already have.
- In Elona+, training a skill this way will always add a flat 100%
- Sleeping in a bed. (You get a dream about raising a skill potential - it raises a flat 5%.)
- Read a scroll of growth, which trains a random skill you have. Blessed scrolls train two skills for 50% more.
- Read a scroll of gain attribute, which can teach you a new skill entirely, or train potential on an existing one. Blessed scrolls will always train a new skill, unless all skills are known; then it will act as an uncursed one.
- Wishing for a skill levels that skill and adds to its potential.
Pet skill potential
Pets can increase their skill potential by spending gold on training; they do this automatically when in any town. For every training they receive 3% of potential in every skill, and 2% in every attribute. They can get gold in several ways:
- Let them pick it up off the ground.
- Put gold in a kitty bank, hrow it, and let them pick it up.
- Let them pick up ores off the ground.
- Give them ores directly via nteracting with them.
Although attributes level more slowly than skills, this is due almost entirely to attribute potential being more difficult to raise. New characters with "Superb" stat gains grow their attributes alarmingly quickly. This, unfortunately, fades all too soon. Since attribute potential is based upon race and class choices, for all but the late game, race and class choices have a larger impact upon attributes than upon skills.
You cannot directly see the potential of your attributes. Instead, you get a word descriptor:
- "Superb" means you have over 200% potential in that stat.
- "Great" means you have 151-200% potential.
- "Good" means you have 101-150% potential.
- "Bad" means you have 51-100% potential.
- "Hopeless" means you have 50 or less potential.
Attribute potential can be trained in the following ways:
- Sleeping is the most common way to increase attribute potential - with any decent bed, you will likely see a "your potential increases __%" message, which indicates potential in attributes rising. Note that percentages indicate total attribute potential gains, so if it says you gained 3% potential, you may have gained 1% potential in three different attributes.
- In Elona+, if you wake up in the morning (between dawn and noon) and you have any pets in your party, one of them will cook you breakfast. This will fill up everyone in the party to "bloated", and increase the attribute potential of everyone in the party. The potential increase scales with the cooking skill of the cook, so you should use Gene Engineering to add that skill to any pets that are going to be in your party.
- Guild trainers who can show up as visitors at Your Home (but only if you've hired a maid) can train a single stat on each visit, for up to three visits a month; the cost is 4 platinum coins if you're the member of no guild, or 3 if you're a member of the guild.
- Adventurers at your home with high impress can train a single stat for 6 platinum.
- Drinking from wells, especially the holy well of Noyel.
- Potions of potential - high-level alchemy skill can let you brew your own... if you can supply the ingredients. Blessing the potions will give you potential to all attributes at the same time.
- Herbs besides the curaria and stomafillia train and raise potential for two attributes at a time. High-level gardening on a farm with herb seeds can potentially give you renewable sources of herbs, especially if you get help from Kumiromi of Harvest for more seeds and gardening skill, and plant during rain.
- Using a training machine increases strength potential.
- In Elona+ using a large picnic basket will increase the attribute potential of everyone in your party.
If you rely upon sleeping alone to raise your potential, odds are good your attribute potentials will fall to Hopeless and stay there.
In standard Elona, spell potential is completely invisible, but exists. Spell levels are important for determining the power of your spells - a Magic Dart at spell level 15 will do around twice as much damage per casting as a level 1 spell. Each spell has its own individual experience and potential scores, meaning that training Heal Light does nothing to boost spell levels for any other spell - even Heal Critical.
In standard Elona, it is unknown why/when spell potential rises. Testing reveals it starts at 200%, and goes down as per normal from there, and that when it goes up, it suffers from a penalty based upon how high it already is. The formula for decline in gained potential is different from the skill potential increase, however - it drops to 1% around 200% potential, but increases more quickly around 100% potential. This may simply be because the base amount of potential increase is a smaller number than the +15% (-1% per 15% you already have) you get for skills when you pay platinum at trainers, making the increase drop to the minimum +1% at lower values.
Elona+ adds a new interface mechanic that allows players to see their spell level potential, and also increases spell potential by 20% in every spell with spell stock remaining every time players sleep. This, along with cheaper spell books and lower spell stock consumption, seems to be geared towards making a wizard less difficult to play. Version 1.59 increased the rate at which spell potential drops when a spell levels up, but to balance this out made it possible to practice spells without expending spell stock by paying platinum to a town wizard NPC for practice sessions.