So About That Fire Buff

In my last entry, I acknowledged that fire mages were getting a buff in 5.2, but admitted that the size of the buff would be hard to calculate. What will happen is Scorch will become a standard fire mage talent, freeing up that talent for a different choice. (It could be said that Frost and Arcane are getting nerfed in this way, as whatever benefit Scorch had over the other Level 15 talents is going away for them.) For the purposes of discussion I’m going to assume that fire mages will choose Presence of Mind (PoM) as their Level 15 talent, both because I think it’s likely the best talent on that tier and also because it seems to be the only one I can even attempt to figure out the boost from.

There is an obvious use case for Presence of Mind.  Its cooldown is one and a half minutes, which is exactly the cooldown of an unglyphed combustion (without the 4pc T14 bonus). It would be used in conjunction with a Pyroblast! buff as follows:

  1. Fireball 1 begins casting.
  2. Fireball 1 launches, Fireball 2 begins casting.
  3. Fireball 1 lands with a crit, activating Heating Up.
  4. Fireball 2 launches, Inferno Blast cast, activating Pyroblast!
  5. Fireball 2 lands.
  6. Presence of Mind is cast.
  7. Pyroblast 1 is cast. using instant cast of the Pyroblast! buff.
  8. Pyroblast 1 lands, getting 25% damage boost from the Pyroblast! buff.
  9. Pyroblast 2 is cast, using the instant cast of the Presence of Mind buff.
  10. Pyroblast 2 lands, but without the typical 25% damage boost.
  11. Combustion is cast.

If Alter time is available, that sequence can be modified as follows:

  1. Fireball 1 begins casting.
  2. Fireball 1 launches, Fireball 2 begins casting.
  3. Fireball 1 lands with a crit, activating Heating Up.
  4. Fireball 2 launches, Inferno Blast cast, activating Pyroblast!
  5. Fireball 2 lands.
  6. Presence of Mind is cast.
  7. Alter Time is cast.
  8. Pyroblast 1 is cast. using instant cast of the Pyroblast! buff.
  9. Pyroblast 1 lands, getting 25% damage boost from the Pyroblast! 
  10. Pyroblast 2 is cast, using the instant cast of the Presence of Mind buff.
  11. Pyroblast 2 lands, but without the typical 25% damage boost.
  12. Alter Time is ended manually, restoring the Presence of Mind and Pyroblast! buffs.
  13. Pyroblast 3 is cast. using instant cast of the Pyroblast! buff.
  14. Pyroblast 3 lands, getting 25% damage boost from the Pyroblast! 
  15. Pyroblast 4 is cast, using the instant cast of the Presence of Mind buff.
  16. Pyroblast 4 lands, but without the typical 25% damage boost.
  17. Combustion is cast.

Without Presence of Mind, you can still use these basic strategies, but there is no Pyroblast 2 or Pyroblast 4 incorporated in the Combustion damage mechanic.  I won’t bother to write those out explicitly.

Now let’s get some damage assumptions.  I’m going to use Jana’s most recent World of Logs performance for these numbers.  She has about 15% haste, which will be important later, and for these assumptions I’m not going to incorporate the higher haste she would get from her Essence of Terror trinket or from Time Warp or Heroism.  The relevant spells are Pyroblast, Inferno Blast and Fireball, and I am taking these figures from her Sha of Fear kill.

  • Pyroblast: hits for 147373.9, crits for 302080.2, 30.9% crit rate. Tick hits for 23022, crits for 47358.7, 32.9% crit rate.  Averaged 4.2 ticks per Pyroblast. Direct damage averaged 195178 (not including ignite).  DoT damage averaged 130321 per Pyroblast.  Total damage per Pyroblast cast equalled 325499.  Assuming this is buffed with the Pyroblast! damage buff, an unbuffed Pyroblast would do, on average, 260399 damage.
  • Fireball: hits for 68832.1, crits for 159524.4, with a 41.6% crit rate.  Total damage per Fireball averaged 106522.
  • Inferno Blast always crits for an average damage of 60861.2.
  • Combustion’s direct damage averages 188927.
  • Mastery is 22.93%, specifying the total value of the ignite buff.
  • Haste is a little below 15%, but we’ll use 15% for simplicity.
  • The Global Cooldown is 1.3 seconds.
  • Fireball has a 1.96 second cast time.
  • Ignite ticks every 1.74 seconds for a total duration of 3.48 seconds.
  • Combustion, for practical purposes, is cast every 2 minutes.

My assumption as to how ignite works is that it will count from the last spell impact. I know this to not be the case because if it were so one could scorch ad infinitum without ever getting an ignite tick.  For the purposes of calculating the ignite tick at a given time, I’ve assumed that the ignite does not tick between the Inferno Blast and Fireball 2, between Pyroblast 1 and Pyroblast 2, and between Pyroblast 3 and Pyroblast 4.  This may not be completely accurate but I suspect it’s so.

Also, for the purposes of comparison I have ignored the DoT component of Pyroblast.  My understanding is that the PoM pyroblast sequences will have a bit extra time for a Pyroblast tick, but subsequent pyroblasts will overwrite the DoTs of earlier pyroblasts, which would actually leave PoM at a slight disadvantage in this regard.

To be clear, here are the four possible sequences in abbreviated form and the fastest time they could be cast (note that neither Alter Time nor PoM activates a global cooldown):

  1. No Alter Time, No PoM: FB - FB - IB - PB - Combustion.  Total cast time: 6.52 seconds.
  2. Alter Time, No PoM: FB - FB - IB - AT - PB - AT - PB - Combustion. Total cast time: 7.82 seconds.
  3. No Alter Time, PoM: FB - FB - IB - PoM - PB - PB -Combustion. Total cast time: 7.82 seconds.
  4. Alter Time, PoM: FB - FB - IB - PoM - AT - PB - PB - AT - PB - PB - Combustion. Total cast time: 10.42 seconds.

For purposes of incorporating lag and my inability to move my fingers at the speed of light, let’s add 0.1 seconds per item clicked, whether or not it’s on the global cooldown. Thus, the times are: 1. 7.02 seconds, 2. 8.62 seconds, 3. 8.52 seconds and 4. 11.52 seconds.

The damage I’ve calculated for each sequence is as follows:

  1. Direct Damage: 711k, Combustion DoT Damage: 567k, Effective DPS: 182k.
  2. Direct Damage: 906k, Combustion DoT Damage: 915k, Effective DPS: 211k.
  3. Direct Damage: 867k, Combustion DoT Damage: 845k, Effective DPS: 201k.
  4. Direct Damage: 1218k, Combustion DoT Damage: `1048k, Effective DPS: 197k

(edit: a previous version of this chart did not incorporate possible combustion DoT crits.  I’ve increased combustion DoT damage by 135% to take into account a reasonable crit rate. I’ll also note that these figures seem a bit high to me, but I think they are proportionately high, in the sense that the relative differences between the two are likely to be the same.) 

This leads to an extremely curious conclusion as to the fourth sequence, in that it suggests that you’re better off not using PoM at all when Alter Time is available. But this isn’t necessarily true, because 173k dps over an 11.52 second interval may be more valuable than 184k dps over an 8.62 second interval.  In fact, let’s go back to Jana’s dps report.  In the Sha of Fear fight (which may not be the best because of the downtime to ominous cackles), Jana had an effective dps of 74.5k during that time.  Since Jana’s 74.5k dps actually includes combustion results, this isn’t exactly right, but let’s use that figure for now figuring combustion dps and Sha of Fear downtime will about cancel out. Assuming these strategies can be used once every two minutes, you get the following results:

  1. No AT, No PoM: 80.8k dps
  2. AT, No PoM: 84.3k dps
  3. No AT, PoM: 83.5k dps
  4. AT, PoM: 86.2k dps

This clarifies the curious conclusion; the AT-PoM sequence may have lower dps than the AT-No PoM sequence, but because it’s a longer sequence it has a greater benefit to overall dps.

So what’s the net boost?  Well, that depends on how many AT combustions versus non-AT combustions you can get.  For a six minute fight, for instance, again assuming combustion is cast every two minutes, you’d get two AT combustions and one non-AT combustion.  An eight minute fight would even them out, as would a four minute fight.  For simplicity, let’s assume there’s an equal chance of three combustions or two or four.  You’d get the following:

  • DPS for 4 minute fight, no PoM = (84.3k * 120 + 80.8k * 120) / 240 = 82.6k
  • DPS for 6 minute fight, no PoM = (84.3k * 240 + 80.8k * 120) / 360 = 83.1k
  • DPS for 4 minute fight, PoM = (86.2k * 120 + 83.5k * 120) / 240 = 84.9k
  • DPS for 6 minute fight, PoM = (86.2k * 240 + 83.5k * 120) / 360 = 85.3k

Thus, PoM results in a 2.8% buff for a 4 minute fight, and a 2.6% buff for a 6 minute fight.  On the average it should be around 2.7%.

It’s not a huge buff, but it’s not a bad one considering that practically no one will recognize that it is a fair size buff and may think that you’re just doing better.

(If anyone would care to run a similar analysis to see if they get a conclusion of the same magnitude, I’d appreciate it a lot. A previous version of this suggested that the buff was slightly greater, in the 3% range. This number was calculated based off of an assumption that combustion DoTs would never crit, which was clearly wrong.)