Theorycrafting 101: Spell Modifications (Buffs and Passives and Talents, oh my!)
by, 28-05-2012 at 03:15 AM (16111 Views)
Hello dear readers, and welcome to what will hopefully be the first of many entries explaining some of the mechanics and maths of Theorycrafting. Our first topic comes from Slowpoker so she doesn't try eating my brain in order to consume all the knowledge (but we know this isn't true because everybody knows there is no such thing as a smart zombie). That topic is: applying buffs, passives/talents, and stat procs to a spell/ability (excuse the brevity, for twitter is not a place to ask large questions).
There are two ways all off these effects apply to spells, with a few exceptions, and they are split by whether they apply at the start or the end of a spell cast (Melee types are primarily using "instant cast spells" for these explanations). The same sort of behaviour applies whether it's a buff, talent, passive, temporary stat buff or whatever.
Generally speaking, most of your spell modifiers will come into play when the spell cast either finishes ("on cast) or hits ("on hit). For example, if you're casting a 3 second Fireball Of Doom (note: spell is totally made up) and 2 seconds into the cast you get another stack on your Awesome Intellect Stack-O-Matic trinket, the damage from your Fireball Of Doom will include the extra intellect gained during the cast time.
However, if you have just cast DoT Of Burnination on a target, and your Awesome Intellect Stack-O-Matic trinket gets another stack, your next DoT tick will not also include that extra intellect. DoTs & HoTs do change with debuffs on the target, but they don't change with player buffs unless you re-cast them. (source)
This sort of behaviour applies to any non time based stat: ie: % Damage, Agility, Strength, Intellect, Crit, Spellpower, Mastery (depending on Mastery bonus, of course).
Lets not be too Hastey
If you said "Haste isn't on that list", it's because it has different behaviour (if you also note that Spirit isn't there then I'll say a) well done, and b) who cares? It's a regen stat and doesn't affect spell casts).
Going back to our two examples from before, in both cases an additional stack on our Amazing Haste Stackatron trinket will do absolutely nothing to our current spell cast or currently active DoTs. This is because the time components of a spell are calculated when the cast/dot starts (mostly so that temporary haste buffs don't cause massive re-calc issues as dots speed up and slow down all over the place). However, this also means that when a haste buff expires mid cast, or after you've cast a dot, the effects of the buff persist while the buff does not.
If you pay attention, you can use this to your favour by making sure you recast all of your dots just before your current haste buff of choice expires (for Elemental Shaman, a good time to do this is just before Elemental Mastery expires).
There are always exceptions to the rules
In certain situations, there are exceptions to what I've described above, and most of these will be specific situations for each class. For example, for Elemental Shaman the Fire Elemental pet will gain your buffs dynamically, meaning that you do not have to cast it when you've got one or more temporary Intellect buffs up, as was the behavior in Cataclysm.
Similarly, the Unleash Flame buff gained from using Unleash Elements with Flametongue Weapon is a damage bonus to your next fire spell, which increases all damage of the next Flame Shock, direct damage & dot, rather than just the direct damage component you would otherwise expect.
But, how does a stat buff differ from a damage buff?
Late addition to the post!
The first thing to remember is that most things are multipliers, so it doesn't matter what order it goes in usually. Buffs adding flat stats like Agi, Crit rating, etc will add on to your "paper doll" stats first, and then feed into the normal calculations from there (ie: if you have a +10% Awesome passive, and you get a +30 Awesomeness stat buff, you gain a net 33 Awesomeness).
Normal order of things is Paper Doll -> Passives -> Buffs -> Debuffs, where each section multiplies with each other section, but adds with things inside it (more on that for another topic).
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