I've been collecting data on the planeswalker vault rotation since mid-July and I thought I'd share some of my observations.
There are currently 24 planeswalkers in rotation (the other 5 are always available). With few exceptions 3 are offered every week. So you would expect to see a given PW about every 8 weeks.
But the rotation is not regular. We haven't seen Garruck for at least the 18 weeks I've been tracking this. And often, they will offer the same PW for two weeks in a row. If you count this as 1 appearance, the average time you'll have to wait goes up to 11 weeks.
Next week we are expecting to see Lilliana Death's Majesty and Nissa Steward of the Elements. There will probably be one other PW that has not yet been announced. This is probably Saheeli Rai or Arlinn Kord.
Not counting Saheeli or Arlinn, the two color PWs we have waited the longest for are: Ajani Vengeant (13 weeks), Tezzeret The Schemer (8 weeks) and Samut (6 weeks).
The longest single color PW waits are: Garruck, Gideon Ally of Zendicar (10 weeks), Tezzeret the Seeker (12 weeks), Jace Unraveler of Secrets (9 weeks), Ob Nixilis (8 weeks), and Gideon of the Trials (7 weeks).
My guess for the week after next is we'll see Ajani, and one of the Tezzs or Gideons. If you're looking for Kiora, Elspeth, Nahiri, or Dovin Baan you probably will have a fairly long wait since they just recently were in the vault.
The new set will likely change this around a bit. It's also possible that the new developers will do this differently than it has been done in the past. But so far they haven't said anything about it.
Rhasget said: Arlinn is in this weeks rotation.Theres always one PW that stays two weeks and I'm guessing they are the more popular/used ones.I would like for all PWs to be visible in each rotation though, even if I own them already. They could just be marked as owned or dimmed or such.We get new players in our coalition from time to time and when discussing what to buy it's harder when you don't see whats on offer or coming in the vault but rather have to locate the webpage.