User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-16281343-20141104122906/@comment-16281343-20141104130622

Another speculation:

Ishi used two things that came from previous Volumes (Vol. 2 and 3), maybe he'll use one again.

I found this in Volume 9

"Really, looks like the proposal Shemhaza has been pushing all along will finally get started"