OK, hear me out here, because if you take some time and track down all information it’s clear this makes sense.
Let’s have a look at what we know.
Initially:
Soulforge started rotating troops from the 2nd week of January. There are 27 mythics and having 4 per week gives about 7 weeks to rotate the pool. So worst case if a troop is at the start of a pool and end of the next is about 14 weeks. Infernus was last seen 8 weeks ago. So it could appear any week now, and is certain to turn up in 6 weeks, assuming troop rotations do not change.
I responded to this with suspicion, as the devs hadn’t confirmed this behavior. It took a while to get a response but:
Sorry we didn’t officially announce this. The Soulforge was adjusted earlier this year so that mythics are now selected from a pool of troops that is only reset once it is empty. This ensures that we rotate through all troops evenly. At 4 troops per week it takes about 7 weeks to empty the pool and start again. For further details on these changes you can read more about sampling without replacement here: https://www.ma.utexas.edu/users/parker/sampling/repl.htm Based off of some historical d…
And, finally:
This is when the pool reset. Our initial pool was not the full listing of 70ish troops as I removed what had been recently available, so that’s why the first reset didn’t take 17 weeks.
So let’s talk about it.
There are 27 total mythics. If 4 are selected every week, that is 27 / 4 = 6.75 weeks per rotation, roughly 7. We are currently in week 17 of 2018, so there has been time for 2 rotations. CliffyA pointed out the first rotation did not contain the full pool of mythics for whatever reason, so it didn’t take a full 7 weeks. He also indicated the 2nd rotation explains Gog and Gud’s repeat appearance on 19 February, shortly after an appearance on 5 Februrary. So that rotation could’ve happened on the 12th or 19th of Februrary.
What’s 7 weeks from those dates? The 2nd or 9th of April. What’s in common about the repetition of the troops you mentioned? Every troop’s “first” appearance in the interesting time range is on or before 19 March. Every troop’s “repeat” appearance happened on or after 9 April. Therefore, these repetitions are in line with what we have been told.
If a rotation happened on the 2nd or 9th of April, the end of the current rotation will be on 28 May or 4 June. We should see Infernus before then. We can pinpoint the date of the rotation if we’re clever: we know for sure our last rotation was the 2nd or 9th of April, so we can look for the first repetitions after that to help nail it down.
So I was wrong with my from-memory recollection of the relevant dates, and I also had a mysteriously wrong mental estimation of the cycle length.