Flame Shock: The damage-over-time component of this ability can now produce critical strikes and is affected by spell haste. (Source)The crit change is trivial since the Current Flame Shock glyph does this for us. Being affected by spell haste is much more interesting (and brain racking). Ok, to be fair it is only brain racking if you have 4P T10.
How does haste affect DoTs?
Taken from the 3.3.0 patch notes (when haste affected DoTs were first introduced):
Shadowform: This talent also now causes Devouring Plague and Vampiric Touch to benefit from haste. Both the period length and the duration of these spells will be reduced by haste.This means that a Hasted DoT will tick faster, causing it to not last as long. Each tick will still do what it normally does damage wise. This is easy peasy to comprehend; it does what it does, only faster.
Why is this an issue?
Our 4P T10 extends the duration of our Flame Shock by 6 seconds. It is my understanding that in reality this adds two ticks to the duration. (As in, DoTs are actually calculated in ticks and normally a tick happens every three seconds giving the illusion of a timed duration.) Others believe that the actual duration of the FlS is increased by 6 and you'll get as many ticks in as will fit.
If it works the way I think it will, then the amount of time we can sustain a single FlS will be reduced because haste doesn't effect spell cooldowns. This creates contradicting messages; T10 4P says "Hey, you don't have to cast FlS as often." which means maybe we could pump up a FlS and keep it rolling for extra damage. The haste change says, "Hey, you have to cast FlS more often. Oh, and you can't sustain it as long with the T10 4P because that 6 seconds isn't actually 6 seconds and your LvB won't be off CD." Obviously this reduces the impact of pumping up an initial FlS through clever use of potions and trinkets.
If it works the way others think it will, then we get an odd situation where the FlS will linger for a bit at the end without doing damage. For example, if the ticks are counting every 2.5 seconds, then extending the duration by 6 seconds will allow for two more ticks (just like the previous example). But those two ticks will only take 5 seconds to complete and then I have 1 second left on my FlS where it does nothing except enable other things to happen (i.e. LvB to crit and T10 4P to extend it again). Eventually that residual would add up to allow for an extra tick as well. I'm almost hoping this is how it works, but I'm not holding my breath.
So what's the point?
I don't think pumping up a FlS at the beginning of a fight will be as beneficial as before because the pumped up FlS cannot be sustained as long. We will end up with a DPS gain though, since doing the same amount of damage faster is what it literally means to have an increase of DPS. Of course, as with everything, there are more factors to consider. Having to cast FlS again eats up a GCD which could have been spent on LB. Does the extra DPS from a hasted FlS equal out to a loss of a LB (and a loss of a 2 sec reduction to EM)? That I'll leave up to the true theorycrafters. I'll just continue to muse.
*The title is Latin for "Make haste slowly." While not exactly what we need to do in this situation, I like the quote because of it's seemingly paradoxical existence. And it does have Haste in it, so cut me some slack.