Oblivion:Spell Making

The ability to make custom spells is one of the most powerful perks that you acquire by joining the Mages Guild.  You can combine multiple effects into a single, powerful spell; you can optimize the strength of spells to minimize the Magicka cost.  There are even versions of some spells that can only be accessed through the Altar of Spellmaking.

A list of suggestions for custom spells can be found at Useful Spells.

Making Custom Spells
Custom spells can only be made at an Altar of Spellmaking. There are two within the Praxographical Center building at the Arcane University. These are only available to members of the Mages Guild who have completed all the recommendation quests in order to gain access to the University. A third altar is available within the Arch-mage's personal quarters in the Arcane University once you complete the Mages Guild quests and become Arch-mage.  A fourth altar is found in Frostcrag Spire, if you have the official plugin, but you must purchase the magetallow candles and upgrade the altar before it can be used.

When you activate the Altar of Spellmaking, the spellmaking window appears. On the left you are presented with a list of all the magical effects you can use to make a new spell. This list only contains the effects of spells that you know and are able to cast (see Acquiring Spell Effects for details).

Select a spell effect, and a new screen pops up where you can set the range (self, touch, or target), area of effect if appropriate, magnitude and duration.  These parameters determine three things: the Magicka cost of casting the spell, the minimum level of skill required in order to cast the spell, and the gold cost of making it.
In the case of Fortify Attribute, Fortify Skill, and similar effects, this screen also allows you to click on the attribute or skill shown in order to choose the desired attribute/skill.

Once you are finished specifying the details, return to the main spellmaking window.  You can then add a second (and third and fourth) spell effect if you wish.  For multiple-effect spells, the overall spell school is the school of the most powerful single effect (using the base magicka cost of the effect, see equation below).

Name the spell and click done. If your skill level is not high enough to cast your custom spell, you will be given an error message and returned to the spellmaking window.  You will be allowed to create a spell that costs more than your total available magicka.  Once done, the new spell will be added to your repertoire.

There is a bug when creating multi-effect spells that may allow you to create a spell even though your skill level is not high enough to cast it.  In determining whether to allow the spell to be created, the game checks the magicka cost of the single most expensive effect, instead of summing all the magicka costs as it should.  Therefore it is prudent to pay attention to the message at the bottom of the spellmaking window that tells you what skill is needed to cast the spell: the message provides the correct information.  There is generally no advantage to creating a spell that you cannot cast: it would cost less gold to create that same spell if you waited until your character's skills were high enough to cast the spell.

The order of different effects can be very important to the custom spells. But some similar magic effects have predetermined order regardless of the order in the custom spell. It's determined by the order in the effect list of the spellmaking window. Interestingly, it's affected by the language used. One example is bound weapon. If you combine all the bound weapon effects in a single spell, you will get a bound axe in the English version, but in French you will get a bound bow (arc in French) instead. Drain effects have a similar impact. This may cause unexpected results with language mods.

Spell Cost
The magicka cost of a spell is given by:
 B = Base Cost / 10
 M = Magnitude ^ 1.28
 D = Duration
 A = Area × 0.15
 Total cost = B × M × D × A

If M, D, or A is less than 1, a value of 1 should be used.  The magicka cost is further multiplied by 1.5 if the spell is a Targeted spell.  Base Cost is as defined in the construction set, see the Spell Effects page. A spreadsheet to calculate the cost is also available from Ong elvin's userpage.

The cost is further adjusted on an individual basis by a multiplier given below:
 1.4 - 0.012 × Skill
Note that the Skill in this calculation is modified first by the player's Luck, and as usual the modified Skill is constrained between 0 and 100.

The gold cost is simply three times the Magicka it costs your character to cast the spell.

So, for example, 3 points of Fire Damage for 12 seconds will cost 36.7 Magicka (Fire Damage has a Base Cost of 7.5) and will deal 36 damage to the target. In comparison, a Fire Damage effect for 6 points and 6 seconds will cost 44.6 Magicka for the same damage. The lesson here is that spells are more efficient when they work over longer durations. Of course, this does make some sense, as the 36 damage would be dealt twice as fast in the second spell.

As a consequence, the Temple-provided "Convalescence" spells have two qualities that are expensive and unnecessary for their purpose of healing allies: they are Targeted spells and have large Magnitude with no Duration. A  more efficient custom spell can be created that is on Touch and with a longer Duration relative to its Magnitude. This is particularly useful for healing your horse.

Note that purchased/given spells sometimes have a different Magicka cost than their custom counterparts. For example, Finger of the Mountain is always overpriced (except for the variant available to players level 1-4), whereas ''Wizard's Fury is cheaper than if made through spellmaking.

The skill level requirement is determined from the base Magicka cost of the overall spell (summing the costs of all individual effects, and without adjusting based on your current skill level):
Magicka < 26: no skill level requirement
26 &le; Magicka < 63: requires skill of 25
63 &le; Magicka < 150: requires skill of 50
150 &le; Magicka < 400: requires skill of 75
Magicka &ge; 400: requires skill of 100
For multi-effect spells, the requirement will be in the school of the single effect with the highest base Magicka cost.  (Therefore in a spell with four alteration effects and one illusion effect, illusion could easily be the school of the spell).  Also, the experience you gain for casting this spell will only be in the primary school.

In multi-effect spells, the skill adjustment is applied to each component effect separately.  Therefore, if your skill level is 100 in Alteration but 25 in Illusion, the Alteration component of a spell will be relatively cheap, but the Illusion component expensive.

If your skill levels are very different in two different schools, multi-effect spells can be used to create spells that otherwise you would be unable to cast.  For example, if you are a master of illusion but a novice in destruction, normally you would be unable to create a Fire Damage 16 pts on touch spell (base magicka cost 26).  However, you would be able to create a spell with a combined Paralyze 6 pts on touch (base magicka cost 285) and Fire Damage 100 pts on touch (base magicka cost 272), because the combined spell would be identified as an Illusion spell.  Actually being able to cast this spell might still be difficult, however, because of the high magicka cost: even for destruction=25, the actual magicka cost would be 356 (285×0.2=57 for the paralyze component, 272×1.1=299 for the fire damage component).

Acquiring Spell Effects
You can only create custom spells using effects of spells that you know and are able to cast.  For example, if your only Restore Health spell is too powerful for you to cast (e.g. it requires Journeyman level in Restoration, and your level is below that), then you cannot choose Restore Health as an effect.

An important point is that the various Attribute-specific spells are considered to all be a single effect.  Therefore, learning Fortify Endurance gives access to all seven Fortify Attribute spells at the Spellmaking altar.  Similarly, the skills are also grouped.  So a single Drain Marksman spell gives access to all twenty-one Drain Skill spells.
The easiest method of acquiring spell effects is to purchase spells from merchants, mages guild members, and chapel healers.

Spell effects can also be acquired from your Greater and Lesser powers (due to Race, Birthsigns or Doomstones).

Details on acquiring difficult spell effects are provided on the pages describing each spell effect.  Two particularly difficult effects to acquire are Fortify Skill and Drain Attribute.

The Fortify Skill effect cannot be bought anywhere in Cyrodiil. However there are many other ways to get access to it. You can make all Fortify Skill spells if you have any Fortify Skill.  The Fortify Skill page provides details on several methods that can be used to obtain this effect.  (Note that Fortify Attribute spells are already readily available for sale throughout Cyrodiil from many spell vendors.  Only Fortify Skill spells are unavailable for sale.)

The Drain Attribute effect cannot be bought from any spell vendor, and there are only four known ways to acquire this effect, as detailed on the Drain Attribute page.  Acquiring Drain Attribute makes some powerful spells available at relatively low costs, since Drain Attribute is much cheaper than Damage Attribute if only a short duration effect is needed.  Note, however, although Drain Endurance can be devastating when cast on the player, it has no effect on the health of any NPCs.

Effective Custom Spells
When creating your own custom spells, there are a few considerations that can help to make your spells more effective.
Weakness does not influence any Damage effects that are included in the same spell.  In other words, you must cast a Weakness spell first, then follow it up with a Damage spell to get the increased damage due to the Weakness effect.
When casting a spell which includes a Weakness to Magic effect onto a target for a second time, the original Weakness to Magic effect will influence all effects in the spell up to and including the Weakness to Magic effect.  Effects listed after the Weakness to Magic effect will not be altered; therefore, it is generally best to make sure that the Weakness to Magic effect is listed last in any spells that you create.
If combining Soul Trap and Damage in the same spell, the Soul Trap effect must be listed first.  Also, the Soul Trap effect must last for one second longer than the Damage effect.
Two Fortify Attribute effects can not be combined in the same spell.  Similarly, two Fortify Skill effects can not be combined in the same spell.
Combining multiple similar effects results in a cheaper spell than a spell with just one strong effect.  In other words, 20pts Fire Damage + 20 pts Frost Damage + 20 pts Shock Damage is a cheaper spell than 60 pts Fire Damage.
A spell with a longer duration is cheaper than a 1 second spell with the same total magnitude.  In other words, 10pts Fire Damage for 6 seconds is cheaper than 60 pts Fire Damage.
Spells with different names can be simultaneously active, even if the spells do the exact same thing.  This is a way to get around the 100 point maximum magnitude for spell effects.
When a window is opened or a conversation is started, any spell effects remain active indefinitely until the window is closed or the conversation ends. In this way, you can use "Fortify Sneak 100 pts for 1 second" to pickpocket almost anything, "Charm 100 pts for 1 second" to maximise disposition, etc.
It can be particularly effective to combine some effects with Invisibility.  For example, a Conjure plus Invisible spell will allow your Conjured creature to deal damage while you remain safely hidden.  Another tactic is to combine an Invisibility effect with an area Frenzy effect to incite a riot among your attackers, leaving you untouched.
For "On Self" spells, adding any "On Touch" effect will give it the much faster "On Touch" casting animation while adding almost nothing to the cost. "Feather'' 1 pt for 1 second" is the cheapest option, and won't anger people if you accidentally cast it on them.

Spell Chaining
 
Chain spells are custom spells that take advantage of the game mechanics, such spells temporally increase the current Magicka by an amount greater than the cost of the spell itself, allowing the player to cast the same spell infinitely.

Chain spells are particularly useful for characters born under the Atronach Birthsign and characters with a small Magicka pool or low Willpower. However the strongest chain versions may be useful for anyone.

A chain spell consists of two sets of effects, the Magicka manipulation, and the desired additional effects. The possible Magicka manipulation effects are:
Fortify Magicka: Temporally adds an amount of Magicka equal to its magnitude to both the current and maximum Magicka.
When the effect dispels the current and maximum Magicka are reduced by that amount, however it can not reduce the current Magicka below zero.
Fortify Intelligence: Temporally increases the Intelligence attribute, effectively increasing both the current and maximum magicka by two times its magnitude.
This is true even when Intelligence surpasses 100.
When the effect dispels the current and maximum Magicka are reduced by two times the magnitude, it is possible to end up with a negative value in the current Magicka this way.
Drain Magicka: Temporally reduces the current and maximum magicka, however it can not reduce the current Magicka below zero.
Its function in spell chaining is to increase the current Magicka. From a negative value, to zero. Also "Drain negative magicka" can act as an extra fortify magicka effect. The magnitude depends on the drained negative value, instead of the set value in the spell.
The additional effects can be anything, the only exceptions are effects already present in the spell. Note that Fortify Intelligence is a Fortify Attribute effect, if Fortify Intelligence is part of the Magicka manipulation, no other Fortify Attribute can be added to the same spell.

Depending on the player's Willpower, it is possible to use chain spells that cost slightly more Magicka than usual due to high Magicka regeneration.
Be aware that wearing armor will reduce the magnitude of your spells, so chain spell effects (other than Fortify Magicka or Intelligence) will have to be adjusted for the spell to have a lower total Magicka cost in order to compensate for the lower Magicka pool.

To effectively spell chain, it is required to cast the same spell before the Fortify Magicka, Intelligence and Drain Magicka effects wear off, otherwise the Magicka pool will deplete and the chain will fail.

Example:
Fortify Magicka 100 pts for 5 secs on Self
Drain Magicka 3 pts for 5 secs on Self
Restore Health 35 pts for 1 sec on Self
With a Restoration skill of 50, this spell would cost 97 Magicka. As long as the same spell is cast again in the 5 seconds time limit, the character's Magicka will never drop below 100. Since the spell's cost is less, you can chain this spell infinitely, restoring 35 Health points on each cast.

Drain Intelligence: Temporally decreases the Intelligence attribute when the magicka is already negative, to further reduce the negative magicka. 1 sec is enough. Since drain magicka will take effect between drain intelligence and fortify intelligence, drain intelligence and fortify intelligence will not really cancel each other out.
After the negative magicka is reset by the drain magicka effect, the expiration of drain intelligence will effectively restore both the current and maximum magicka by two times its magnitude.

Example 2:
Fortify Intelligence 100 pts for 13 secs on Self
Fortify Magicka 100 pts for 13 secs on Self
Drain Magicka 3 pts for 120 secs on Self
Drain Intelligence 100 pts for 1 sec on Self
(Other effects, total cost =< 500 pts)
After casting a few times, drain magicka will become "drain magicka (-)700 pts for 120 secs" in the active effect list. The maximum magicka will be greater than 1500 pts, considering the original magicka and two fortify effects. Then, repetitively casting the spell or not, with 100 Willpower (it takes 12 seconds to replenish 1/3 of the maximum magicka), the character's magicka will never drop below 500 pts after 1 second (end of drain intelligence), due to the natural regeneration.

This only works when "drain attribute" is above "drain magicka" in the magic effect list (alphabetical order). So it won't work in some translated versions of the game. If it fails in some languages, editing the magic effect name with some modder tools should make it work.

Spell Stacking

One way of making super-powerful spells is by stacking spells.  This is based on two facts:
Effects from spells with different names stack by adding together.
Weakness to Magic amplifies any following harmful spell, including weakness to magic itself.

To use spell stacking you need to start by making three custom spells.
#Prepare 1:
#*Weakness to Fire 100% for 5 secs on Touch
#*Weakness to Magic 100% for 5 secs on Touch
#Prepare 2: 
#*Weakness to Fire 100% for 5 secs on Touch
#*Weakness to Magic 100% for 5 secs on Touch
#Fatality:
#*Fire Damage 10 pts for 10 secs on Touch

If you prefer, you can use any other effect for the Fatality spell. If you change to Frost Damage or Shock Damage, change the "Prepare" spells to use Weakness to Frost or Weakness to Shock, respectively.  Or you can change Fatality to use any other damaging effect: Absorb Health, Disintegrate Armor, Paralyze, etc.  Drain Health 100 pts for 1 secs is normally a near useless spell, but it quickly becomes a cheap kill effect when pre-buffered by enough Weakness to Magic Prepare spells.

Now depending of the toughness of an enemy, you may cast longer or shorter spell combinations:
Fatality.
Prepare 1, Fatality.
Prepare 1, Prepare 2, Fatality.
Prepare 1, Prepare 2, Prepare 1, Fatality.
Prepare 1, Prepare 2, Prepare 1, Prepare 2, Fatality.
Prepare 1, Prepare 2, Prepare 1, Prepare 2, Prepare 1, Fatality.
Prepare 1, Prepare 2, Prepare 1, Prepare 2, Prepare 1, Prepare 2, Fatality.

The table below shows how much damage every combo provides.



An attentive reader may notice that second Prepare 1 should replace first Prepare 1. It is true. The spells with the same names replace each other. However, second Prepare 1 is boosted by enemy's weakness to magic, so "lighter" Prepare 1 is replaced by "heavier" Prepare 1 and the new, heavier one stacks with the previously cast Prepare 2.

Spell Stacking on Self
:This exploit no longer works after the version 1.1 patch has been installed. Weakness to Magic no longer amplifies any effects cast on Self.
Spell-stacking can also be used upon yourself to greatly amplify beneficial effects, however it needs a trick. Only harmful effects are modified by your magic resistance/weakness. A spell becomes harmful when you include a damaging effect into it. Add a weak damaging effect to a strong boosting spell and it will be multiplied by your weakness to magic. Weakness to Magic on Self is a harmful spell too. 

Here is one example of this technique. Make three spells:
#Boost 1: 
#*Weakness to Magic 100% for 5 secs on Self
#Boost 2: 
#*Weakness to Magic 100% for 5 secs on Self
#Dragon Being:
#*Weakness to Frost 3% for 1 secs on Self
#*Fortify Health 50 pts for 120 secs on Self

Adjust Dragon Being spell strength according your Restoration level.

Dragon Being may fortify whatever you need most: Magicka, Willpower, Strength, Luck, magic resistance, Shield, Skill, Chameleon, spell reflection, spell absorption.  (Note that many of these effects receive no benefit for values greater than 100, so this technique is of limited use with these.)

Now cast a chain that suits your needs:
Dragon Being
Boost 1, Dragon Being.
Boost 1, Boost 2, Dragon Being.
Boost 1, Boost 2, Boost 1, Dragon Being.
Boost 1, Boost 2, Boost 1, Boost 2, Dragon Being. 
Boost 1, Boost 2, Boost 1, Boost 2, Boost 1, Dragon Being.
Boost 1, Boost 2, Boost 1, Boost 2, Boost 1, Boost 2, Dragon Being.

This table shows the strength of these combos:


To fortify Magicka you may use just a simple spell with three components:
Fire Damage 3 pts for 1 secs on Touch
Fortify Magicka 100 pts for 3 secs on Self
Weakness to Magic 100% for 3 secs on Self
Cast it several times on a summoned skeleton.  After that you should (temporarily) have enough magicka for any powerful Master level spell.