I has a theory: Halfus Wyrmbreaker is not random.
I discovered, as many others before me, that the drakes are not random per raid ID - they're the same across your realm. I also figured out quickly that they're the same in 10-man and 25-man (easy to test, just check, run out, switch difficulties, check again).
Based on comments and forum threads on here, I also figured out (as many others have) that they're the same across regions. US and EU seemed to have different combinations.
So I figured, just in case, let me look through World of Logs and see if it is possible that there is a pattern. I mean what's the worst that could happen, I waste two hours for nothing? (I do that a lot.)
The results were... interesting. I later tried to add in TW and KR to confirm my analysis, but their drakes appeared to be the same as the EU at first glance (note: I could be wrong on TW and KR, I only looked at maybe 3-5 TW and KR logs compared to 50+ of the others).
Weeks:
Week 1: 12/7 - 12/13
Week 2: 12/14 - 12/20
Week 3: 12/21 - 12/27
Week 4: 12/28 - 1/3
Week 5: 1/4 - 1/10
Week 6: 1/11 - 1/17
Week 7: 1/18 - 1/24
Week 8: 1/25 - 1/31
EDIT/NOTE: For EU, all these weeks are off by one day due to the Wednesday reset vs Tuesday reset, so:
12/8 - 12/14, 12/15 - 12/21, 12/22 - 12/28, 12/29 - 1/4, 1/5 - 1/11, 1/12 - 1/18, 1/19 - 1/25, 1/26 - 2/1
are the correct weeks, in order from 1 to 8 for EU guilds. Sorry about that.
US Drakes by Week
Storm Rider, Time Warden, Whelps
Nether Scion, Storm Rider, Whelps
Nether Scion, Slate Dragon, Whelps
Slate Dragon, Storm Rider, Whelps
Nether Scion, Slate Dragon, Time Warden
Slate Dragon, Storm Rider, Time Warden
Nether Scion, Storm Rider, Time Warden
Nether Scion, Storm Rider, Slate Dragon
EU/KR/TW Drakes by Week
Nether Scion, Storm Rider, Time Warden
Nether Scion, Slate Dragon, Storm Rider
Slate Dragon, Time Warden, Whelps
Nether Scion, Time Warden, Whelps
Storm Rider, Time Warden, Whelps
Nether Scion, Storm Rider, Whelps
Nether Scion, Slate Dragon, Whelps
Slate Dragon, Storm Rider, Whelps
Potential Drake Cycle Pattern
Nether Scion, Slate Dragon, Time Warden (Week 5 in US) (Week 9 in EU/KR/TW)
Slate Dragon, Storm Rider, Time Warden (Week 6 in US) (Week 10 in EU/KR/TW)
Nether Scion, Storm Rider, Time Warden (Week 7 in US) (Week 1 in EU/KR/TW)
Nether Scion, Storm Rider, Slate Dragon (Week 8 in US) (Week 2 in EU/KR/TW)
Slate Dragon, Time Warden, Whelps (Week 9 in US) (Week 3 in EU/KR/TW)
Nether Scion, Time Warden, Whelps (Week 10 in US) (Week 4 in EU/KR/TW)
Storm Rider, Time Warden, Whelps (Week 1 in US) (Week 5 in EU/KR/TW)
Nether Scion, Storm Rider, Whelps (Week 2 in US) (Week 6 in EU/KR/TW)
Nether Scion, Slate Dragon, Whelps (Week 3 in US) (Week 7 in EU/KR/TW)
Slate Dragon, Storm Rider, Whelps (Week 4 in US) (Week 8 in EU/KR/TW)
This week is Week 8. Here at the ones you should have had (or will have, based on when you raid this week):
US: Nether Scion, Storm Rider, Slate Dragon (based on my guild's logs and the rest of my server)
For EU, other. guilds'. logs. confirm. this: (note all five totally different servers, and differing difficulty modes)
EU: Slate Dragon, Storm Rider, Whelps
Next week is Week 9, and the bolded ones are me trying to predict the future.
This means that If I'm right, next week's drakes will be:
US: Slate Dragon, Time Warden, Whelps
EU/KR/TW: Nether Scion, Slate Dragon, Time Warden
I was planning on posting this next week, but I want to post this now just for proof (or counter-proof) when the week changes.
Anyone have any experiences contradictory to this? Is this old information? (I didn't see it anywhere else.)