It seems that stamina dedicated packs are available every other day. I have been regularly purchasing them recently to hit Ass. 6's for their material. Repeatedly even to get to Legendary. And to hit Alpha's like Possessed for their jewels. (Turquoise, study boosts.)

I have been buying 'Source of Stamina! 50% Discount!' at 6.49 for 210k stamina.

I understand there is also a 'For Assailant Killers!' which may have more stamina at that price point. I don't recall ever seeing it. Does anyone know how to trigger changes in the pack offerings between these (apparent) streams?

I also understand that the 25.99 equivalent pack has better than 4 times that amount of stamina in it. I have read that once one buys a 25.99 pack, the 25.99 equivalents to the 6.49 packs I currently see will show up. [*Not strictly true.] Yet no 25.99 pack is of interest to me, especially as I do not wish to feed additional troops. Suggestions?

* Not strictly true - I know I have bought one or more 25.99 (or 6.49?) sale pack, be it Black Friday, Boxing Day, or Valentine's Day, I forget which. Doing so does not appear to have impacted my regular 6.49 selection.