Frostfire plays Fire's crit-driven priority with 
Frostfire Bolt as the filler. 
Fire Blast goes on cooldown, 
Scorch keeps five stacks of Fire Vulnerability, 
Pyroblast fires when three crits have made it fast, and the bolt fills every gap. Mana sets the pace on longer fights.
Before the pull
- 1At -2.6 s: Cast Frostfire Bolt
Start a Frostfire Bolt 2.6 seconds before the pull. It casts in 2.5 seconds with 
Improved Fireball and lands a moment after the pull, worth 3.4 % of your damage on a one-minute single-boss fight. Keep 
Mage Armor on all fight: in Forever half your mana regeneration carries on while you cast.
Priority
Whenever you are free to cast, go down the list and take the first line that is ready and true. The widget shows every line with its casts and what it adds.
- 1Cast
Mana Ruby if mana % ≤ 100%1.0/min– - 2Cast
Combustion if Fire Vulnerability stacks ≥ 51.0/min+33 DPS · 4.1 % - 3Use the other cooldowns as they come up+33 DPS · 4.2 %
- 4Cast Pyroblast if
Heating Up stacks = 32.8/min+39 DPS · 4.9 % - 5Cast Pyroblast if Heating Up stacks ≥ 2 and (time remaining < 6 s or Heating Up remaining < 3.5 s)2.8/min–
- 6Cast Fire Blast if mana % ≥ 10%9.1/min+45 DPS · 5.6 %
- 7Cast Scorch if Fire Vulnerability stacks < 5 or Fire Vulnerability remaining ≤ 8 s6.7/min+142 DPS · 17.8 %
- 8Cast Frostfire Bolt if mana % ≥ 10%13/min+356 DPS · 44.8 %
The lines that need a reason:
- Pyroblast at three Heating Up stacks. A crit from the bolt, Fire Blast or Scorch cuts a quarter off its six-second cast, so the third stack leaves a 1.5-second cast of your largest hit. The line is worth 4.9 %. A second Pyroblast line spends two stacks, a three-second cast, when they are about to run out or the boss is about to die.
- Fire Blast on cooldown, every 6 seconds with Wake of Fire. It is instant, and its crits build Heating Up too. The rotation stops casting it only when your mana is nearly gone. It is worth 5.6 %, and you need to stand within 20 yards of the boss to cast it.
- Scorch below five Fire Vulnerability stacks, or with 8 seconds left on them. Each stack is 3 % more Fire damage from you for 30 seconds, and the bolt takes it in full. After the first five Scorches you need one about every 22 seconds, so on this fight it comes to about 6.7 a minute. The line is worth 17.8 %.
- Frostfire Bolt in every other gap, worth 44.8 %. It is 41.0 % of your damage on this fight.
More than one target
Against three bosses the bolt gives way to 
Flamestrike. On a three-minute fight against three bosses it does 50.6 % of your damage, 
Blast Wave goes out whenever you are within 10 yards, and Fire Blast, Scorch and the three-stack Pyroblast stay where they are. Switch the guide to a three-boss fight to see that list.
Cooldowns
Combustion is the only damage cooldown on one minute. It waits for the fifth Fire Vulnerability stack, around the ten-second mark, and lasts until three Fire crits use it up. The line is worth 4.1 %.
Talisman of Ascendance goes out at the pull and each minute after. For 20 seconds each spell you cast adds 40 spell damage to the ones after it, five times at most. 
Robe of the Archmage, 
Demonic Rune, 
Major Mana Potion and the gems each have a cooldown of their own and go out as your mana bar drops. The table shows when each went on this fight.
On one minute the Mana Ruby's line fires at any mana, so the gem goes at the pull: its two-minute cooldown can't come round again anyway.
| Cooldown | Uses | At |
|---|---|---|
| Mana Ruby | 1 | 0:00 |
| Talisman of Ascendance | 1 | 0:00 |
| Robe of the Archmage | 1 | 0:08 |
| Combustion | 1 | 0:11 |
| Demonic Rune | 1 | 0:19 |
| Major Mana Potion | 1 | 0:42 |
What your log should show
Compare your own Warcraft Logs report with this table.
Bolts a minute show your casting time, Fire Blasts a minute whether you let it sit, and Pyroblasts a minute whether your Heating Up stacks ran out.
| Ability | Casts per minute | Of damage | Crit |
|---|---|---|---|
| Frostfire Bolt | 13.5 | 41.0 % | 31.9 % |
| Fire Blast | 9.1 | 20.4 % | 37.7 % |
 Ignite | 10.0 | 14.8 % | 0.0 % |
| Pyroblast | 2.8 | 14.3 % | 32.2 % |
| Scorch | 6.7 | 9.5 % | 31.6 % |
| Talisman of Ascendance | 1.0 | – | – |
| Demonic Rune | 1.0 | – | – |
| Combustion | 1.0 | – | – |
| Robe of the Archmage | 1.0 | – | – |
| Mana Ruby | 1.0 | – | – |
| Major Mana Potion | 1.0 | – | – |
Here a clean log shows about 13.5 bolts a minute, 9.1 Fire Blasts and 2.8 Pyroblasts, and Ignite close to 14.8 % of the damage. The bolt's line counts its damage over time as well as the hit.
Uptimes
| Buff or debuff | Uptime | Times per fight |
|---|---|---|
| Fire Vulnerability | 94.8 % | 6.1 |
| Frostfire Bolton the boss | 85.7 % | 12 |
| Heating Up | 67.8 % | 9.1 |
| Igniteon the boss | 51.3 % | 10.0 |
| Pyroblaston the boss | 40.9 % | 2.5 |
| Ascendance | 34.3 % | 1.0 |
| Ascendance | 33.3 % | 1.0 |
| Combustion | 20.0 % | 1.0 |
Fire Vulnerability should sit near 94.8 %. Let it fall and every Fire spell, the bolt too, hits 15 % softer until Scorch has stacked it again. Heating Up shows about 67.8 %, because a stack can sit for 20 seconds before a Pyroblast spends it.