This data was collected by Warcraft Logs from May 30th to June 3rd, with the specific snapshot of data below being collected on June 4th around the weekly reset time.
Bastion of Twilight OverviewBlackwing Descent OverviewThrone of the Four Winds Overview
Heroic Difficulty Curve
To start, we can look at the number of kills on Heroic for both 10 and 25-player modes.
10 Player Heroic Kills
25 Player Heroic Kills
In both difficulties, the easiest boss to begin progression on is Halfus Wyrmbreaker, with over 2100 kills on 10-Heroic and over 1800 kills on 25-Heroic.
After that, the next step seems to be the first five bosses in Blackwing Descent, with Magmaw and Atramedes being the easiest ones, followed by Omnotron Defense System, Chimaeron, and Maloriak. While the progression happens all in Blackwing Descent, Maloriak has half as many kills as other bosses, but the progression is fairly linear.
The next step in the difficulty curve is Valiona & Theralion and Conclave of Wind. After that, difficulty ramps up, and discrepancies begin between 10 and 25.
For 10m, Al’akir seems to be the easiest choice here, followed by Cho’gal and Ascendant Council. Note that while all Heroic bosses are required to kill Sinestra in Bastion of Twilight, you can kill normal Ascendant Council and then Heroic Cho’gall, which seems to be the choice for some guilds, as Cho’gall is easier and the loot is superior to Ascendant Council. The final bosses then are Nefarian and Sinestra, both with around 110 kills each during week one.
For 25m, Al’akir seems to have a similar difficulty to Sinestra and Nefarian, leaving Ascendant Council and Cho’gall as the next step after Conclave of Wind. After those, then 25m raids head into Al’akir, followed by Sinestra and Nefarian.
Population Comparison
One interesting aspect of the data is comparing the number of groups doing 10 and 25-player content. With lockouts shared in Cataclysm, players need to choose between 10 or 25-player raids for their characters. For Normal mode, we have almost 90,000 10-player kills between all Tier 11 raids while only having a little over 37,000 25-player kills logged. If you normalize for raid size, there’s an even split in the number of players doing 10 and 25-player normal raids, which leads to a larger number of 10-player kills due to roster size.
For Heroic, the numbers change drastically. During the first week, there were 10,892 10-player Heroic kills logged and 10,058 25-player Heroic kills logged, which means that more than double the number of players doing 25-player Heroic content than 10-player Heroic content.
Difficulty Per Boss
The data offered by WarcraftLogs allow us to compare the number of attempts logged per boss versus the number of kills on each boss, offering a good insight on the average number of pulls each boss takes to die per difficulty and raid size.
10-Player Normal
25-Player Normal
10-Player Heroic
25-Player Heroic
The first thing you’ll notice from those charts is the ramp-up in difficulty that is Nefarian on Normal mode for both 10 and 25-player raids. It represents a steep increase in difficulty and challenge for groups in every raid size.
Looking at Heroic, it is interesting to notice that every boss takes, on average, more attempts to kill in 10-player Heroic than in 25-player. This can be an indication of 10-Heroic being more difficult or perhaps that the best players prefer to do 25-player content. More research is required to pinpoint the cause of it.
Raw Data
10-Player Normal
| Boss | Kills | Wipes | Kill % | Parses | Pulls per Kill |
| Omnotron Defense System | 8093 | 595 | 93.2 | 8688 | 1.07 |
| Atramedes | 7666 | 1450 | 84.1 | 9116 | 1.19 |
| Cho’gall | 8189 | 1961 | 80.7 | 10150 | 1.24 |
| Theralion and Valiona | 8159 | 2380 | 77.4 | 10539 | 1.29 |
| Halfus Wyrmbreaker | 6473 | 2141 | 75.1 | 8614 | 1.33 |
| Conclave of Wind | 6368 | 2775 | 69.6 | 9143 | 1.44 |
| Al’Akir | 6897 | 4271 | 61.8 | 11168 | 1.62 |
| Magmaw | 7353 | 5370 | 57.8 | 12723 | 1.73 |
| Maloriak | 8321 | 6481 | 56.2 | 14802 | 1.78 |
| Ascendant Council | 8371 | 10697 | 43.9 | 19068 | 2.28 |
| Chimaeron | 8180 | 12203 | 40.1 | 20383 | 2.49 |
| Nefarian’s End | 5869 | 67545 | 8 | 73414 | 12.51 |
25-Player Normal
| Boss | Kills | Wipes | Kill % | Parses | Pulls per Kill |
| Omnotron Defense System | 3599 | 175 | 95.4 | 3774 | 1.05 |
| Halfus Wyrmbreaker | 2204 | 207 | 91.4 | 2411 | 1.09 |
| Atramedes | 2978 | 281 | 91.4 | 3259 | 1.09 |
| Theralion and Valiona | 3268 | 676 | 82.9 | 3944 | 1.21 |
| Cho’gall | 3284 | 748 | 81.4 | 4032 | 1.23 |
| Conclave of Wind | 2522 | 895 | 73.8 | 3417 | 1.35 |
| Maloriak | 3604 | 1695 | 68 | 5299 | 1.47 |
| Magmaw | 3381 | 1836 | 64.8 | 5217 | 1.54 |
| Ascendant Council | 3404 | 2550 | 57.2 | 5954 | 1.75 |
| Al’Akir | 2681 | 2835 | 48.6 | 5516 | 2.06 |
| Chimaeron | 3533 | 5762 | 38 | 9295 | 2.63 |
| Nefarian’s End | 2804 | 19960 | 12.3 | 22764 | 8.12 |
10-Player Heroic
| Boss | Kills | Wipes | Kill % | Parses | Pulls per Kill |
| Halfus Wyrmbreaker | 2162 | 18682 | 10.4 | 20844 | 9.64 |
| Magmaw | 1698 | 27168 | 5.9 | 28866 | 17.00 |
| Atramedes | 1644 | 10090 | 14 | 11734 | 7.14 |
| Omnotron Defense System | 1220 | 17352 | 6.6 | 18572 | 15.22 |
| Chimaeron | 995 | 11690 | 7.8 | 12685 | 12.75 |
| Maloriak | 857 | 6619 | 11.5 | 7476 | 8.72 |
| Theralion and Valiona | 742 | 15733 | 4.5 | 16475 | 22.20 |
| Conclave of Wind | 656 | 15510 | 4.1 | 16166 | 24.64 |
| Al’Akir | 270 | 7345 | 3.5 | 7615 | 28.20 |
| Cho’gall | 217 | 2288 | 8.7 | 2505 | 11.54 |
| Ascendant Council | 208 | 6111 | 3.3 | 6319 | 30.38 |
| Nefarian’s End | 115 | 4467 | 2.5 | 4582 | 39.84 |
| Sinestra | 108 | 2661 | 3.9 | 2769 | 25.64 |
25-Player Heroic
| Boss | Kills | Wipes | Kill % | Parses | Pulls per Kill |
| Halfus Wyrmbreaker | 1840 | 11645 | 13.6 | 13485 | 7.33 |
| Atramedes | 1663 | 7146 | 18.9 | 8809 | 5.30 |
| Magmaw | 1395 | 21307 | 6.1 | 22702 | 16.27 |
| Omnotron Defense System | 1171 | 11234 | 9.4 | 12405 | 10.59 |
| Chimaeron | 1009 | 7821 | 11.4 | 8830 | 8.75 |
| Maloriak | 918 | 4387 | 17.3 | 5305 | 5.78 |
| Theralion and Valiona | 647 | 11131 | 5.5 | 11778 | 18.20 |
| Conclave of Wind | 483 | 8803 | 5.2 | 9286 | 19.23 |
| Ascendant Council | 235 | 5752 | 3.9 | 5987 | 25.48 |
| Cho’gall | 233 | 3353 | 6.5 | 3586 | 15.39 |
| Al’Akir | 174 | 4466 | 3.8 | 4640 | 26.67 |
| Sinestra | 153 | 2352 | 6.1 | 2505 | 16.37 |
| Nefarian’s End | 137 | 3807 | 3.5 | 3944 | 28.79 |