Skills

Magicka Sorcerer Buff Analysis
Magicka Sorcerer Buff Optimizer

Magicka Sorcerer Buff Analysis

For a Magicka Sorcerer, there are really just 4 buffs that stand out and get a lot of attention on a number of builds:
Skill Line Unmorphed Effects
Bound Aegis Daedric Summoning Bound Armor +8% Magicka, +2% Spell Damage
Power Surge Storm Calling Surge +20% Spell Damage, +2% Spell Damage
Structured Entropy Mage's Guild Entropy +20% Spell Damage, +2% Magicka
Inner Light Mage's Guild Magelight +10% Crit Chance, +5% Magicka, +2% Magicka

The values above and the calculations that follow assume a very developed late-game Sorcerer, namely one which makes use of the following passives:

Skip the math

The Math

The unmitigated damage dealt by a skill can be determined by the following: 
    Skill Damage = SkillCoefficient * (Magicka + 10.46 * SpellDamage)
With a crit modifier: 
    Effective Damage = K * (M + 10.46 * S) * (1 + CritChance * CritDamage)
For the sake of simplicity, we will drop the skill coefficient and just refer to the '10.46' as some constant A, giving us this formula for 'base damage': 
    Base Damage = (M + AS) * (1 + CD)

For starters, we will look at just 3 of the buffs, excluding Inner Light because its crit chance buff complicates the math considerably. Let's apply these buffs and see how they affect the base damage expression:

Aegis 

    New Base Damage = (M + 0.08M + A * (S + 0.02S)) * (1 + CD)
                    = (M + AS + 0.08M + 0.02S) * (1 + CD)
                    
    Difference      = (0.08M + 0.02AS) * (1 + CD)

Surge 

    New Base Damage = (M + A * (S + 0.22S)) * (1 + CD)
                    = (M + AS + 0.22S) * (1 + CD)
                    
    Difference      = 0.22AS * (1 + CD)

Entropy 

    New Base Damage = (M + 0.02M + A * (S + 0.20S)) * (1 + CD)
                    = (M + AS + 0.02M + 0.20S) * (1 + CD)
                    
    Difference      = (0.02M + 0.20AS) * (1 + CD)
In the context of comparison, we can ignore the crit modifier (1 + CD) since all 3 buffs have it. Moving foward with this simplification, let's start by comparing Aegis and Surge. Recall that A = 10.46 from above. 
    Aegis > Surge if:   0.08M + 0.02AS >  0.22AS
                        0.08M          >  0.20AS
                            M / AS     >  0.20 / 0.08
                            M / AS     >  2.5
                            M /  S     > 26.15
In other words,

Bound Aegis provides a greater damage increase than Power Surge if the ratio of base Magicka to base Spell Damage is at least 26.15

Here, 'base' Magicka is the amount of Magicka with all additive buffs (e.g. enchantments, Mundus Stones, etc.), but without multiplicative buffs (e.g. skills, racial passives, etc.). The same applies for Spell Damage.

To put this 26.15 ratio into perspective, let's say we have 1500 base Spell Damage. In order for Bound Aegis to be favored over Power Surge, we would need 39,225 base Magicka, which is quite a lot compared to how low 1500 Spell Damage is.

Let's repeat this exercise for Aegis and Entropy: 

    Aegis > Entropy if: 0.08M + 0.02AS >  0.02M + 0.20AS
                        0.06M          >          0.18AS
                            M / AS     >          0.18 / 0.06
                            M / AS     >          3.0
                            M /  S     >         31.38
Compared to Structured Entropy, Bound Aegis is even worse! At 1500 base Spell Damage, we would need 47,070 base Magicka to favor Bound Aegis over Structured Entropy, which is an astronomical amount. To formalize our findings:

Bound Aegis provides a greater damage increase than Structured Entropy if the ratio of base Magicka to base Spell Damage is at least 31.38

Based on these ratios, we can already start to guess which is the better of the two between Entropy and Surge. But let's do the math to get a better idea: 
    Surge > Entropy if:         0.22AS >  0.02M + 0.20AS
                                0.02AS >  0.02M
                         0.02 / 0.02   >      M / AS
                                1.0    >      M / AS
                               10.46   >      M /  S
Most players will find that their base Magicka to Spell Damage does exceed this ratio, mostly because Magicka has benefits that Spell Damage does not offer (e.g. providing a larger resource pool, increased shield strength) and should be prioritized as such. As a result, Structured Entropy will provide a greater damage increase than Power Surge in a majority of cases.

Power Surge provides a greater damage increase than Structured Entropy if the ratio of base Magicka to base Spell Damage is less than 10.46

All the analysis that we've done up to this point only considered the 3 buffs which do not affect any critical stats, which in turn allowed us to ignore half of the base damage formula presented in the beginning. If we bring Inner Light into the picture, the complexity of the comparisons grows considerably due to the fact that we are now parameterizing 4 variables, as opposed to 2. In light of this, the rest of the math is more easily determined by means of simulation rather than variable manipulation, at which time I defer to the Buff Optimizer.

Buff Optimizer

Disclaimer: I just want to point out that the analysis above and the calculations that are involved in this optimizer are from a purely damage-centric standpoint. You should take the findings of this post with a grain salt because it fails to address other valuable effects that all of these skills provide. From the perspective of sustainability, the ranking of these buffs is most likely very different. At the very least, this is just a fun means of applying math to a game that allows for extremely open-ended build diversity.

How many abilities on your bar are you willing to assign to buffs?