Oblivion:Alchemy

Alchemy is one of the seven skills that make up the Magical Arts in Oblivion. This skill allows you to identify the different effects of all the ingredients that you find in Cyrodiil. These ingredients can then be used to make potions and poisons. The potency and price of the potions and poisons that you make is determined by your Alchemy skill level. Selling potions and poisons that you have created is one of the easiest and most efficient ways to get gold in the game.

In-game Description: Create potions and gain benefits from alchemical ingredients more effectively.

Alchemy's governing attribute is Intelligence, but Intelligence has no effect on the potency of the potions that you make (this is very different from earlier Elder Scrolls games such as Morrowind). Furthermore, boosts in Alchemy caused by enchantments (potions, spells, or equipped constant effect items) have no impact on the potions that you make; the Altar of Alchemy in Frostcrag Spire is the one exception, which will improve your potions.

You can consume up to four potions at one time. This number does not increase at higher alchemy levels. However, you can drink an unlimited number of potions if you hot-key them, as long as the potions don't have duration effects. Otherwise, you will need to wait until one of the effects has run out to start drinking again. An unlimited number of ingredients can be eaten at once. Potions without duration effects that aren't hot-keyed can also be drunk more than four at a time if you close and then re-open your inventory.

Potions can be very powerful. For example, at the highest levels and with the best equipment, a Restore Health potion can restore 559 points of Health and a Restore Magicka potion can restore 1872 points of Magicka.  A Damage Health poison can cause 240 points of damage, and this amount can be more than tripled in combination with other damage effects. Therefore, investing some time in Alchemy will unlock some of the most powerful effects available in-game.

If you would like to experiment with what types of potions and poisons are possible, try using the  . This calculator provides information on the strengths of the various effects and the ingredients that can be used to obtain them. For more information, see the Alchemy Calculator page.

You may find a number of other calculators on the net. For easy playing with variations of recipes, you may try for example Darliandor's Alchemy Lab or just another one.
 
Mastery
Mastery Perks
A Novice (Alchemy   
 Effective_Alchemy = Alchemy_Skill_Level + 0.4*(Luck_Level-50)
The   is set by the character's base levels of Alchemy skill and Luck (i.e., completely ignoring any active Fortify, Damage or Drain effects), and has a maximum value of 100 and minimum of 0.  (The only Fortify Alchemy alchemy effect that will make a difference is the Alchemical Brilliance spell of Frostcrag Spire's Altar of Alchemy; even with the altar, however, your maximum   is still capped at 100). Note that attributes such as Intelligence do not have any effect.

It seems that Bethesda intended to use this simple equation to determine a base magnitude ( ) and base duration ( ) for any effect; these base values would be applicable for a given   and quality of Mortar and Pestle.  Then a set of Master Equations would be used to add in the effects of all the other apparatus (Retort, Alembic, and Calcinator).  However, in implementing this system, Bethesda seems to have made a few mistakes, so, in fact, the system is overly complex, with several exceptions that crop up in various situations.

To start with, there are several different equations for the base magnitudes and base durations.  Some effects (Duration-Only Effects) only have a Duration (Magnitude always = 1).  Other effects (Magnitude-Only Effects) only have a Magnitude (Duration always = 1).  For the remaining effects, the base duration is defined to be four times the base magnitude.  Subsequent sections detail the exact equations used to determine the base magnitudes and base durations for each of these situations.  These equations have all been incorporated into the  , if you would like an easier way to figure out a given effect's magnitude and duration.

Caveat: The following equations have not yet been tested on a Master Calcinator (they have been thoroughly tested for all other 19 pieces of alchemy equipment).  However, there is no reason to believe that they should not apply equally to a Master Calcinator.

Master Equations
Taking the base durations and magnitudes (as provided in subsequent sections), the master equations are then:
  Magnitude = Base_Mag * (1 + Calc_Fac*Calcinator_Strength
                            + Ret_Mag_Fac*Retort_Strength
                            - Alem_Fac*Alembic_Strength)
  Duration  = Base_Dur * (1 + Calc_Fac*Calcinator_Strength
                            + Ret_Dur_Fac*Retort_Strength
                            - Alem_Fac*Alembic_Strength)
The   and   factors are always zero for negative effects; the   factor is zero for all positive effects and for all poisons (Alem_Fac only affects negative side effects in potions, although the presence of the Alembic will affect poisons - see below).  However, as detailed below, there are multiple exceptions to these equations.  See here for an explanation of potions versus poisons, but the short version is that a poison has no positive effects and a potion has at least one positive effect.  Note that since the only Magnitude-Only effect, Dispel, is considered positive, so there are no Magnitude-Only poisons.

In all cases, the final magnitudes and durations are rounded such that 4.5 is rounded up to 5; 4.49 is rounded down to 4.  The minimum values for the duration and magnitude are always 1.

The following table provides the factors to use in this equation.


 

The exceptions, described in more detail below, occur when using a Calcinator and a Retort simultaneously on a positive effect which is not Duration Only, or when using an Alembic on a negative effect which is not Duration only.

This results in the following multiplicative modifiers to Base_Mag and Base_Dur:



Most Effects
This section provides the equations for effects where both the magnitude and duration are variable (which are the vast majority of available effects).

For both positive and negative effects, at any   level and for any Mortar and Pestle quality, the base magnitude and duration are determined from:
 Base_Mag =   (Effective_Alchemy + MortarPestle_Strength*25)/(Effect_Base_Cost/10 * 4)   ^ (1/2.28)
 Base_Dur = 4 * Base_Mag

The Master Equations are only applicable when using just a Mortar and Pestle and Calcinator. (Pieces of equipment with no effect can also be added without invalidating the Master Equations, i.e. a Retort for calculating negative effects or an Alembic for calculating positive effects)

There are two exceptions, however, when alternate equations must be substituted for the standard master equations

Exception 1: For positive effects when using ''both a Calcinator and Retort, a special factor,  =1.4, is used instead of  =.35 (note these equations can not be used with  =0):
  Magnitude = Base_Mag * (1 + Calc_Mag_Fac*Calcinator_Strength
                            + Ret_Mag_Fac*Retort_Strength)
  Duration  = Base_Dur * (1 + Calc_Fac*Calcinator_Strength
                            + Ret_Dur_Fac*Retort_Strength)

Exception 2: For negative effects when using an Alembic, the equations become (note these equations can not be used with  =0):
  Magnitude = Base_Mag * (1 + Calc_Fac*Calcinator_Strength)
                       * (1 + Calc_Fac*Calcinator_Strength
                            - Alem_Fac*Alembic_Strength)
  Duration  = Base_Dur * (1 + Calc_Fac*Calcinator_Strength)
                       * (1 + Calc_Fac*Calcinator_Strength
                            - Alem_Fac*Alembic_Strength)
Note that the Calcinator effect is included twice in both of these equations.  These equations apply for negative effects in potions (i.e., unwanted side effects), in which case the equations are used as is.  These equations are also used for poisons (i.e., any concoction which consists solely of negative effects), in which case   is always set to zero.  This means that poisons are affected by adding an Alembic (the quality of the Alembic does not matter, just that you have it in your inventory).

Some implications of these equations for the negative side effects of potions:
A potion made with a Novice Alembic can actually have stronger negative side effects than a potion made with no Alembic at all (if you are using an Expert or Master Calcinator).
Using an Expert Alembic will always cause a 100% reduction in the magnitude and duration of side effects; therefore, the magnitude and duration of all side effects will be 1 (reductions past 1 are never possible).
A Master Alembic is no better than an Expert Alembic (both cause all side effects to have magnitude and duration of 1).

Duration-only Effects
For several effects only the Duration is variable (i.e., Magnitude is always 1).  These effects are Invisibility, Night-Eye, Paralyze, Silence, Water Breathing and Water Walking.

For both positive and negative effects, at any   level and for any Mortar and Pestle quality, the base duration is determined from:
 Base_Dur = (Effective_Alchemy + MortarPestle_Strength*25)/(Effect_Base_Cost/10)

For duration-only effects, the master equation works exactly as advertised.

In other words, the Alembic quirks mentioned under Most Effects for negative effects do   apply to Paralyze and Silence effects.  For these two negative effects, adding an Alembic has no effect on poisons.  Furthermore, an Alembic will always decrease the strength of any negative side effects in potions.

Magnitude-Only Effects
For one solitary effect, Dispel, only the Magnitude is variable (i.e., its Duration is always 1).  Just to guarantee confusion, this one effect has its own set of governing equations.

For both positive and negative effects (not that negative Magnitude-Only effects are actually available), at any   level and for any Mortar and Pestle quality, the base magnitude is determined from:
  Base_Mag =   (Effective_Alchemy + MortarPestle_Strength*25)/(Effect_Base_Cost/10)   ^ (1/1.28)

The master equations work for Dispel as long as a Calcinator and Retort are not used simultaneously.  But if using both a Calcinator and Retort, a modified equation is required (this equation can not be used with  =0 or with  =0; because Dispel is a positive effect, an Alembic makes no difference):
  Magnitude = Base_Mag * (1 + Calc_Fac*Calcinator_Strength
                            * Ret_Mag_Fac*Retort_Strength)
  Magnitude = Base_Mag * (1 + 0.3*Calcinator_Strength
                            * 0.5*Retort_Strength)
  Magnitude = Base_Mag * (1 + 0.15*Calcinator_Strength
                                  *Retort_Strength)
Yes, the effects of the Retort and Calcinator are multiplied''' together here, not added.  Although this is probably a mistake on Bethesda's part, this is the equation that governs Dispel potions.  Therefore, the strongest Dispel potions are actually made using a Retort alone (because 0.5 > 0.3); adding a Calcinator weakens the Dispel effect.

Tips
The system for making potions is simpler in Oblivion than it was in Morrowind. If you have an ingredient selected and you click an empty space to add another ingredient it shows the ingredients that have matching properties. This means that you can make money (and increase both your Alchemy and Mercantile skills) by buying an alchemist's entire stock and matching them to make potions. Even poisons can be sold. Then any leftover ingredients can be either sold back to the merchant or kept to carry on to the next session.
Unlike Morrowind, created potions will only contain the ingredients' known effects according to your Alchemy skill. Hidden effects are completely ignored (in Morrowind hidden effects would still be applied to the final potion).
Combining ingredients that have only negative effects in common creates a poison. You can apply it to a weapon (bow/sword) and the next attack will apply the poison's effect to the enemy, often causing massive damage of proportions very hard to achieve by other schools of magic. The disadvantage of poisons is that their effect is usually distributed over time (i.e., the enemy may take several seconds to die). Note that if combined ingredients have at least one positive effect in common, the effect is a "spoiled potion" (one with both positive and negative effects), not a poison, and can not be applied to a weapon. This may cause poisons that are possible to make at lower levels become unavailable at higher levels, as positive effects of ingredients get unlocked.
Once you reach Journeyman or higher, your ability to create complex potions and poisons is greatly increased. Effects will be added to your potion if you are combining more than one ingredient with that effect. You do not seem to gain anything by using more than two ingredients with the same effect (potion strength seems to be the same), but you can combine different damage effects (fire, frost, shock, health damage) for greater strength of a poison.
For example, with an Alchemy skill of 50 (can see three effects), consider combining Harrada (Damage Health, Damage Magicka, Silence), Spiddal Stick (Damage Health, Damage Magicka, Fire Damage), and Vampire Dust (Silence, Resist Disease, Frost Damage) together. The resulting poison will have the combined effects: Damage Health + Damage Magicka + Silence. Note that you cannot make a potion when enemies are nearby.
If you make a potion out of stolen ingredients, the resulting potion is not flagged as being stolen.

Messages
The following table provides the messages that are displayed when your Alchemy skill levels up.



Useful Potions
For lists of useful potions that can be made, see Useful Potions.