Monday, March 8, 2010

Spell Power Coefficients & The Invisible Hand of Balance

This installment on spell power coefficients argues that the hidden nature of spell coefficients makes spell effects hard to understand for players. The argument is essentially this:
  1. There is no in-game source of information to distinguish spells with larger or smaller than normal coefficients
  2. Inconsistent wording and design of talents makes it hard to know how those talents affects spells
  3. Therefore the only way to access information about how your spells work is by calculating it from data, making the information non-transparent
One could argue that this isn't necessarily a bad thing, but I think that a) there is a good case to be made that transparency of the effect your gear has on your character is a good thing and b) WoW developers have clearly come in favour of transparency, for example, their justification for removal Armor Penetration Rating as a stat. When announcing that Armor Penetration Rating would be removed they used two arguments. One was that it was just a straight dps increase that happened in the same way as attack power increases dps and therefore was unnecessary. The other was that the calculation of it was too complicated and lacked transparency. If a lack of transparency is bad with Armor Penetration Rating, it is bad for spell coefficients as well.

Spell tooltips are not so kind as to include the coefficient of the spells. For the most part spells follow the cast time divided by three and a half rule, but some spells have a higher or lower coefficient and there isn't a way to know which ones or by how much. For example, Lightning Bolt and Starfire have typical coefficients. Arcane Barrage and Vampiric Touch have unusually high coefficients. Shadow Word: Pain and Mind Flay have slightly lower than typical coefficients. In the case of Vampiric Touch the coefficient is actually double the expected value of 100%.

There is no way to know this by looking at the spells. When a shadow priest hits level 50 and takes Vampiric Touch, she also learns a new rank of Shadow Word: Pain that deals 606 damage over 18 seconds. The base level Vampiric Touch deals 450 damage over 15 seconds. That's 101 vs. 90 damage per tick. Shadow Word: Pain is the harder hitting spell. A level 50 character typically does not have a lot of spell power. An heirloom staff, chest and shoulder total 73 spell power at that level. Depending on how dedicated a player is to gear it is easy to imagine having 150 spell power, but more commonly spell power would be closer to 100, or more like 50 for those who aren't handing off gear from higher level characters. Shadow Word: Pain gets 18.3% of your spell power per tick while Vampiric Touch gets 40%. So the first-time player who is just going through in their questing greens will probably find that in reality SW:P deals about 110 damage per tick and Vampiric Touch mysteriously deals pretty much the same. A player who is fairly tricked out for levelling - we aren't talking twink gear but enchanted heirlooms and craftables - is going to do about 128 per tick with SW:P and 150 with Vampiric Touch.

By the time we are level 80 and wearing good gear we already know that, as I said last time, base spell damage numbers are largely just window dressing for talents, glyphs and other effects of the spells. In this case, however, there is nothing in the tooltip for either spell, in any talent or glyph, that would indicate that VT is the harder hitter of the two. Unless they strip naked, any level 80 character is going to get more damage per tick with VT, but nothing in the game explains why.

On the subject of those talents that determine the real power of the spells, they themselves are far from transparent in their effects. There are two different things a talent can mean when it says it increases the spell power coefficient of a spell. They even appear in the same talent tree. Here is Empowered Touch from the druid restoration tree:

Your Healing Touch spell gains an additional 40% and your Nourish spell gains an additional 20% of your bonus healing effects.

And here is Empowered Rejuvenation from further down the tree:

The bonus healing effects of your healing over time spells is increased by 20%.

The difference is this: If the coefficient of a spell were 50% and I said to increase it by 20%, what would you think I meant? Would you think I meant to add 50% and 20% together to get 70% or to increase the 50% by 20% of 50% to get 60%? In the first case, they mean the former, in the second case they mean the latter. Of course the wording of the two talents is different, maybe we are supposed to know how they work from the different phrasing.

Here are some other wordings that appear on actual talents: "Increases the benefit from spell power gained by X by Y%"; "Increases the effect of X by an amount equal of Y% of your spell power"; "The spell power bonus to X is increased by Y%"; "Your X gains an additional Y% of your bonus damage effects"; "Your X gains an additional Y% of your bonus spell damage."

This confusion over what a percentage increase to a coefficient means even appears in two different ways of increasing the coefficient of a single thing. It's not spell power, but a Death Knight has two ways of increasing the amount of her Strength that her ghoul gains, one "Increases the contribution your ghouls get from your strength by Y%" and with the other "Your ghoul receives an additional Y% of your strength." To save you from looking it up, the former is the talent, and it means it increases the base 70% of your strength you share with your ghoul by Y% (Y = 20) of the 70% per point (or 60% of the 70% meaning 42% for all three points, giving a total contribution of 112%) while the latter is the glyph and means a flat add of Y% (Y = 40) of your strength to the ghoul's strength (so 110% of your strength is added for just the glyph without the talent). The talent is applied and then the glyph is applied so that the total contribution if 152%. If the glyph were applied first - and while this may seem counter-intuitive there is nothing in the game that says it isn't - you would instead add 176% of your strength to your ghoul's strength. Both things also affect stamina, but the base contribution from stamina is only 30%, so the final total is 88%. The talent and glyph have exactly parallel wording on Strength and Stamina, but the talent increases the ghouls' strength slightly more than the glyph does while it increases the ghoul's stamina by less than half as much as the glyph does.

There is no consistent wording or way to tell which is which. Moreover, even if you can tell which is which, since you don't know the spell power coefficient of spells to begin with, you don't know what half of these talents actually do.

This means that a person who wants to know how their spells work needs to go to a website and read formulas. This is precisely the behaviour that they want to prevent by getting rid of Armor Penetration Rating. Armor Penetration Rating isn't actually any harder to understand than spell power. For someone who isn't coding a spreadsheet or simulation tool, they both work the same way: having more is better because it makes you do more damage. In fact, the actual effect of Armor Penetration is to understand. There is one, admittedly complicated, formula. Any class that uses spell power usually needs at least three, sometimes more, equally complicated formulas that are no more transparent or available within the game.

Compounding this problem is that fact that spell power coefficients are used as balance tools. Back in BC mages paid the infamous coefficient tax on Fireball and Frostbolt. If they invested in the talents that lowered their cast time, these spells suffered a 5% penalty to their spell power coefficient. This was documented in a set of patch notes but was not indicated within the game. When shadow priests weren't doing enough damage in Wrath one of the fixes was to increase the coefficient of Vampiric Touch to the incredible 200% I mentioned earlier. This certainly upped Shadow Priest damage but it also took a spell that reads like it is meant to do weak damage (you cast it to get replenishment, not for it's punch) and turned it into one of the highest damage per cast spells in the game. At the same time they left Shadow Word: Pain with a sub-normal coefficient and subsequently made it the only shadow priest DoT unaffected by haste; the reasoning on that would really interest me.

I know in my last post I specifically advocated for varying spell coefficients, so it may seem strange that I am now complaining about them varying spell coefficients. But I am not suggesting the remedy to this problem is making spell coefficients uniform. Rather, I think spell coefficients should vary in a way that is consistent with and predictable (at least in a ballpark fashion) from the base spell. Hard hitting spells should have larger coefficients while weaker spells have smaller ones. That way looking at the base spells would give you an idea of the spells' comparative power. Of course this would involve retooling the power of the base spells (Mind Blast should not do triple the dps of Mind Flay) as well. Talents that modified one spell and not another would clearly change this balance, but presumably you know which talents you took and understand that taking a talent that makes Frostbolt more powerful but doesn't affect Fireball will increase the power of Frostbolt relative to Fireball.

Once this is done, all talents that modify spell power coefficients should be worded in one way and mean the same thing.

Furthermore, spell tooltips should show the total damage of the spell given your current gear as well as your current talents. Rather than my mind flay tooltip indicating that it does around 600 damage, it should probably say it does around 6000 damage, since that's the actual truth. Melee abilities show damage numbers based on current gear, it's time for spells to join them.

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