In this post I will try to explain why I chose this approach to the implementation of the essence system, their properties and making potions.

Effects of Essences

First question, should essences have magical effects?

Initially, as your can read in this post, i decide not include any effects for base/collected essences.

As you can read in many lore books, all items of our world can be used for alchemy. Herbs, vegetables, flowers, mushrooms, human and creature parts - all of this has own properties, magic power. Some to a greater extent, some to a lesser extent. It's based on myth of world's creation -  Nirn/Mundus was created by god's power, so all of this created with magic, and contain it.

This means that the nature of the abilities of all living races is also magical, conditioned by centuries of evolution, and is contained in their bodies, body parts, bodily fluids.

So now, in current version, i decide add all effects of each race to essences.

As example, Argonian race, has initial (at character creation) bonuses for this skills - +10 for Lockpicking, +5 for Alteration, Light Armor, Pickpocket, Restoration, Sneak. also they have passive Waterbreathing ability, higher unarmed damage, disease resist 50%. So essences, collected from this race, will have this/simillar effects.

Power and Cost of Effects

The second question is, how strong should the effect be, what should be its magnitude/area/duration?

This is a rather difficult question. Answer based on correct game balance. And main problem - effects cost.

For Argonian's essences example, it can have effect  "Waterbreathing (AlchWaterbreathing)" - one of most expensive game effects. It has base cost value 30, so if you add this effect with duration 5 minutes, you get item with min price 1264 gold. And it only first effect! 

In game, passive abilities actually costless, but related alchemical effects (if exists) can be very expensive. My main rule is not to set extra objects/effects if you can do without them. So if i have effect in game - i use it. If you introspect all usage of this alchemy effect in game you see next. 4 vanilla/base DLC ingredients have this effect with duration 5 seconds, and 1 ingredient with duration 60 seconds. Rare Curious has 6 ingredients with this effect and duration 8 secs. Also game have 4 standard waterbreathing potions with duration 15/30/45/60 seconds, and 1 HearthFire food with effect duration 50 seconds.

So for game balance, the added ingredients should not be significantly stronger than the specified/exist ingredients/potions. Or we receive fully imbalanced gameplay.

Effect's cost is a one of the base game characteristics, which manage many gae aspects - cost of items and potions, skill experience and other mechanics.

One of methods of fast alchemy boosting - create more expensive potions, with expensive effects. 

And related problem - what magnitude/area/duration/base cost i should set to newly createed effects, which not exists in game? For aphrodisiacs, complex potions, transformation potion, perfumes? 

Therefore, if I used the standard alchemy mechanics to create potions from my ingredients, then even with a simple improvement in the quality of the essence, I would get huge alchemy experience and a very expensive potion.  It also almost fully break game balance.

But at the same time, these essences are rare, they are not as easy to get in the game as the rest. So they should have a higher value, give stronger effects.

Craft by recipes at custom workbench

In the end, in order to avoid a lot of problems, I decided to use the recipe system for creating potions.

• All of essences are Ingestible (Potion, ALCH). So you can't combine it with other ingredients on usual alchemical workbench.
• It also got rid of the 4 magic effect limit that exists in the game for all Ingredient (INGR) type objects. Each race has a significant bonus to one of the main skills, as well as several others, and even passive abilities. And it is desirable to add most of them, as available potion/essence effects.
• The production of potions and other mixtures, including intermediate ingredients, is carried out on a special alchemy table. You do not gain standard alchemy experience using this equipment.
• This protects against game balance disturbances associated with an overestimated gain of alchemical experience, the creation of too expensive potions.
• Since I have disabled the standard alchemy experience gain when crafting on this alchemy table, an alternative script to control the crafting process has been implemented. He controls not only the acquisition of alchemical experience, but also the mechanisms for obtaining additional results, sided products, higher quality products, the mechanism for returning the original ingredients.
• To achieve the necessary logic, the script combines the technique of controlling the player's inventory and using custom meta-objects that are replaced with real production results, as it works in harvest scripts for planters in HearthFire.
• When producing according to recipes, it is easier to control, adjust the balance of prices and effects. We always know the price of the original ingredients, and we always know what result we are guaranteed to get. And we can mathematically justify all the changes.
• In addition, in the lore of the game there are references to many effects even for existing ingredients that are not actually in it. Making according to recipes made it possible to "reveal" these effects, to pre-process ingredients to obtain new properties.

On top of that, an interesting way of adjusting ingredient prices has been devised that will add value to an ingredient without having to create an imbalance with overly strong effects. This method consists in adding a special effect that does not actually perform any effect on the gameplay at this stage.

In fact, this is a common effect for all essences, which tracks the statistics of their consumption and calculates the experience of the corresponding skill. Previously, it was without a price, but I decided to add an effect cost to it and use it to adjust the prices of individual essences and potions.

Perhaps in the future I will get rid of this temporary solution (an empty effect with a cost). After all, in fact, in order to perform any action when consuming a potion, it is not at all necessary to add a magical effect to it - all this can be done from the player's control script. But at the moment, until the effects of all essences are balanced, this is the optimal solution.