***UPDATE***
On PTS, set bonuses to healing done have been adjusted to 4%, however the ritual mundus stone and the powered weapon trait still remain at 10% and 9%, respectively. These values need to be adjusted to 1.85x of the set bonus to healing done (~7.4%) to bring them in line with the other mundus stones and weapon traits in order to resolve the inconsistency.
This post is in regards to the 2-4 pc item set bonus, 2% healing done, being both completely outclassed by the 2-4 pc item set bonus of 129 spell damage in all realistic scenarios and also wildly inconsistent in terms of its relationship to its corresponding mundus stone, the ritual, and weapon trait, powered, when compared to similar 2-4 pc item set bonuses and their respective mundus stones and weapon traits.
TL;DR
The 2-4 pc item set bonus, 2% healing done, is mathematically inferior to the 2-4 pc item set bonus of 129 spell damage in all realistic scenarios, in all aspects (including boosting the user's healing done, ironically). Furthermore, neither the healing done mundus stone (the ritual) nor the healing done weapon trait (powered) share the same 1.85x relationship all other mundus and weapon traits share with their corresponding 2-4 pc item set bonuses. Nor are these two healing done resources weighted at the same value, as all other mundus stones and their related weapon traits are.
To remedy this, two possible options come to mind.
Option 1:
The 2-4 pc item set bonus to healing done should be bumped up to 4% healing done to better match it's healing received/taken counterparts, and both the ritual mundus stone and the powered weapon trait should be adjusted to 1.85x of this value, or 7.4% healing done.
Option 2:
Alternatively, the 2-4 pc item set bonus can be reverse engineered from the current ritual mundus stone. This would result in the 2-4 pc item set bonus to healing done being valued at 5.4%, and would require both that the powered weapon trait be brought up to speed with the ritual mundus (to 10% healing done), and also that the 2-4 pc item set bonuses to healing taken and received be boosted to 5.4% to better match their healing done counterpart.
Healing Done vs. Spell Damage
The math:
The healing power of spells can be determined by using the formula for average damage overtime, but slightly modified:
Healing Power = (SpellDamage*%modifiers*10.5+MaxMag*%modifiers)*HealingDone*(1+CritDamage*CritChance)
Using this as a template, we are able to derive formulas that can be used to calculate the effectiveness of both a set bonus to spell damage and a set bonus to healing done.
Spell Damage Set Bonus:
Healing Power = [(SpellDamage*%modifiers*10.5+MaxMag*%modifiers)+129*%modifiers*10.5]*HealingDone*(1+CritDamage*CritChance)
Healing Done Set Bonus:
Healing Power = (SpellDamage*%modifiers*10.5+MaxMag*%modifiers)*(HealingDone+.02)*(1+CritDamage*CritChance)
By setting these two equations equal to each other, we are able to solve for the breakpoint at which a set bonus to healing done equals the exact value of a set bonus to spell damage in terms of healing done:
[(SD*%modifiers*10.5+MaxMag*%modifiers)+129*%modifiers*10.5]*HealingDone*(1+CHD*CHC) = (SD*%modifiers*10.5+MaxMag*%modifiers)*(HealingDone+.02)*(1+CHD*CHC)
The critical multipliers cancel out, so we are left with:
[(SD*%modifiers*10.5+MaxMag*%modifiers)+129*%modifiers*10.5]*HealingDone=(SD*%modifiers*10.5+MaxMag*%modifiers)*(HealingDone+.02)
By filling in some variables, we are able to solve for an exact value of spell damage at which the healing value of 2% healing done is equivalent to the healing value of 129 spell damage. In order to do this, however, we must make some assumptions. These assumptions will be made off of the stats of most endgame healer builds. They are as follows:
-Major Sorcery for 20% spell damage
-Max cp increase for 20% max magicka
-Minor mending for 8% healing done
-30k max mag (as this a benchmark for most healers)
Filling these in, we are left with:
[(SpellDamage*1.2*10.5+30000*1.2)+129*1.2*10.5]*1.08=(SpellDamage*1.2*10.5+30000*1.2)*1.1
(SpellDamage*1.2*10.5+30000*1.2)+129*1.2*10.5=(SpellDamage*1.2*10.5+30000*1.2)*1.0185
129*1.2*10.5=.0185*(SpellDamage*1.2*10.5+30000*1.2)
1625.4=.0185*(SpellDamage*1.2*10.5+30000*1.2)
87771.600=SpellDamage*1.2*10.5+30000*1.2
51771.600=SpellDamage*1.2*10.5
4108.857=SpellDamage
So, given our assumptions, we have determined that at 4,108.857 spell damage, the addition of 2% healing done adds the equivalent healing value of the addition of 129 spell damage. If a healer has more spell damage than this, 2% healing done will out-perform 129 spell damage. If a healer has less than this amount of spell damage, however, 129 spell damage will add a larger bonus to healing than 2% healing done.
Assuming that a healer is running major sorcery, receiving the full benefit of the cp increase to max resources, running minor mending, and has 30k max magicka, the spell damage required on a build to allow a 2% healing done set bonus to perform on the same level as a 129 spell damage set bonus is around ~4109. Any more spell damage than this would give the advantage to the healing done set bonus, but any less spell damage would give the advantage to the spell damage set bonus.
The problem? The 4,000 spell damage mark is very nearly impossible to obtain for healers, so in almost all realistic scenarios healers are better off running 129 spell damage over 2% healing done if they want to increase their healing. But not only does 129 spell damage provide more healing power, it also provides more damage to their damage dealing abilities. So why would anybody run 2% healing done if it would result in both less healing potential and also less damage than a generic spell damage bonus?
Given the very specialized nature of healing done in comparison to the more general use of spell damage, it seems only fitting that bonuses to healing done provide a larger benefit to healing abilities than bonuses to spell damage. Currently, this is not the case, as bonuses to spell damage provide a larger benefit to both healing abilities and damage abilities. Spell damage is getting the best of both worlds.
It is important to note, however, that bonuses to healing done do affect proc heals (from item sets like briarheart/earthgore and things like crit surge on sorcs and siphoning attacks on nb) while spell damage does not. This is the lone advantage healing done holds over spell damage, and it is so niche and miniscule that it does not provide enough of a benefit to compete with bonuses to spell damage.
The Mundus Stone Dilemma
Even more concerning is the inconsistency between 2-4 pc item set bonuses to healing done and the ritual mundus. All other mundus stones give a benefit equal to about ~1.85 2-4 pc item set bonuses:
2028 magicka = 1.85*1096 magicka
238 spell damage = 1.85*129 spell damage
238 magicka recovery = 1.85*129 magicka recovery
7% critical chance = 1.85*3.8% critical chance (833 weapon critical)
But when it comes to the ritual mundus and healing done, the numbers are far off:
10% healing done = 5*2% healing done
Further inconsistency arises when you consider the powered weapon trait. In all other cases in which a weapon trait grants a similar bonus to a mundus stone, the 2h weapon trait value exactly mirrors the mundus value.
The thief=7% crit chance, 2h precise=7% crit chance
The lady=2752 resistance, 2h defending=2752 resistance
The lover=2752 penetration, 2h sharpened=2752 penetration
But the ritual grants 10% healing done and the 2h powered trait only offers 9%.
So what gives? Something definitely seems off about this item set bonus.
What should be done?
Probably the easiest solution would be to work backward from either the ritual mundus or the 2h powered trait to reverse engineer a more appropriate 2-4 pc item set bonus.
Let's look at the ritual mundus first. Doing this would yield ~5.4% healing done as a proper 2-4 pc item set bonus:
10%/1.85=~5.4%
But this seems like a pretty wonky number. Let's take a look at the 2h powered trait.
9%/1.85=~4.8%
This too isn't a very clean number.
Perhaps, then, we can double check which value of these is the better fit by also looking at 5 pc item set bonuses that grant bonuses to healing done. We already know from 5 pc item set bonuses like hundings rage that 5 pc bonuses are typically worth ~2.31 2-4 pc item set bonuses (299 weapon damage/129 weapon damage=2.31).
But there are no 5 pc bonuses that give a flat bonus to healing done, outside of healers habit which is a peculiar case because it grants a minor/major buff in minor mending, and not a flat bonus to healing done. Furthermore, reverse engineering a 2-4 pc item set bonus from this 5 pc bonus yields a different number: ~3.4%.
This supports neither the value the ritual mundus suggests nor the one the powered trait denotes. But, as mentioned earlier, I am skeptical of the accuracy of this 5 pc set bonus because it grants a minor/major buff (and potentially frees up a skill slot) and not a regular flat bonus to healing done. Perhaps their are other similar 5 pc item set bonuses that we can consider.
No other 5 pc bonuses provide healing done, but one does provide healing received to all group members, which is comparable to healing done because it effectively provides the same bonus to your healing abilities as a bonus to healing done would. This set is the sanctuary set. The 5 pc bonus is as follows: increases healing received by 12% for you and your group members within 10 meters of you.
Now this isn't the cleanest comparison either, as this is a conditional proc set (group must be within 10 m of you). We do know, however, that the values of conditional proc sets can be increased by up to 25% of a more regular 5 pc item set bonus, resulting in 5 pc bonuses of this type typically being valued at ~2.8875 2-4 set pc bonuses. What do we get when we reverse engineer a healing done 2-4 pc item set bonus from the sanctuary 5 pc?
12%/2.8875=~4.15% healing done.
This adds up with neither the ritual mundus stone, nor the powered weapon trait, nor the healer's habit 5 pc bonus and only further contributes to the inconsistencies regarding healing done.
By comparing all of these different values, however, I feel we are given a general idea of where the healing done 2-4 pc set bonus should be valued at. They all seem to be bouncing around the values of anywhere between 3.4% to 5.4% healing done.
This would conceivably make sense, as it fits in line nicely with the similar 2-4 pc item set bonuses to healing taken and received, which both grant 4%. We know ZOS likes to re-use numeric values for similar bonuses too, as evidenced by the 2-4 pc item set bonuses to both spell/weapon damage and magicka/stamina recovery each granting a numeric value of 129. Therefore, given that 4% falls within the range of the inconsistencies regarding healing done and also that the current bonuses to healing taken/received grant the same amount, the 2-4 pc item set bonus to healing done could very believably be valued at 4%.
But what does the math say? Does it remedy the uselessness of the current 2% bonus to healing done when compared to spell damage and support this notion?
Math:
[(SpellDamage*1.2*10.5+30000*1.2)+129*1.2*10.5]*1.08=(SpellDamage*1.2*10.5+30000*1.2)*1.12
(SpellDamage*1.2*10.5+30000*1.2)+129*1.2*10.5=(SpellDamage*1.2*10.5+30000*1.2)*1.0370
129*1.2*10.5=.0370*(SpellDamage*1.2*10.5+30000*1.2)
1625.4=.0370*(SpellDamage*1.2*10.5+30000*1.2)
43885.800=SpellDamage*1.2*10.5+30000*1.2
7885.800=SpellDamage*1.2*10.5
625.857=SpellDamage
This indicates that the break point (when the value of 4% healing done = the value of 129 spell damage) occurs when a build has a total of ~626 spell damage, assuming they are running major sorcery, receiving the complete cp increase to max resources, running minor mending, and have 30k max magicka. If a build has more than ~626 spell damage, 4% healing done holds the advantage. If a build has less than this amount of spell damage, 129 spell damage holds the advantage.
Given that even just equipping a cp160 weapon of any type grants more than this amount of spell damage, it is safe to say that bumping the 2-4 pc item set bonus to healing done upwards to the value of 4% healing done would allow this bonus to provide more healing done than a similar bonus to spell damage in all realistic scenarios. The bonus of 129 spell damage, however, would still hold the clear advantage in terms of damage dealing abilities, while also improving the potency of heals (although not as much as healing done would).
Using the same assumptions and formulas as we did earlier (but changing the healing done bonus from 2% to 4%), we find that, strictly in terms of healing abilities, 4% healing done would out-perform 129 spell damage in all realistic scenarios, while 129 spell damage would still offer the clear advantage of improving the potency of damage dealing abilities in addition to a less potent increase in healing. It would seem then that changing the 2% healing done bonus to at the very least 4% healing done would provide a tradeoff between spell damage bonuses and healing done bonuses that is currently not there: if a healer wants to boost their healing power to the highest possible value, 4% healing done would be preferable over 129 spell damage, but if a healer wanted a more general boost to the effectiveness of all of their abilities, 129 spell damage would be chosen at the cost of max healing potential.
This solution seems to solve our problem.
My Proposal
The way I see it, there are two possible solutions to this problem.
Option 1:
The 2-4 pc item set bonus of 2% healing done should be bumped up to 4% healing done to better match its healing received and taken 2-4 pc item set bonus counterparts. Consequently, both the ritual mundus stone and the powered weapon trait should be standardized off of this 4% mark, consistent with how all other mundus stones and weapon traits are valued at 1.85 of their corresponding 2-4 pc item set bonuses. This would result in their values being adjusted to ~7.4% healing done. This would not only give the 2-4 pc item set bonus to healing done more viability in comparison to bonuses to spell damage, but also fix the inconsistencies surrounding this bonus regarding the ritual mundus stone and the powered weapon trait.
It would also, however, result in a nerf to both the ritual mundus and also the powered weapon trait.
Option 2:
Alternatively, the 2-4 pc item set bonus can be reverse engineered from the current ritual mundus stone. This would result in the 2-4 pc item set bonus to healing done being valued at 5.4%, and would require both that the powered weapon trait be brought up to speed with the ritual mundus (to 10% healing done), and also that the 2-4 pc item set bonuses to healing taken and received be boosted to 5.4% to better match their healing done counterpart.
It is important to note, however, that if this option is chosen, certain 5 pc bonuses to healing received/taken must also be adjusted in order to preserve the current balance of 5 pc bonuses being valued at 2.31 2-4 pc item set bonuses for flat stat bonuses and 2.8875 2-4 pc item set bonuses for conditional proc bonuses.
Notable 5 pc bonuses that must be adjusted accordingly belong to:
-Sanctuary: 12% -> ~15.6%
-Twilight's Embrace: 10% -> ~12.5%