As already mention, I wouldn't count too much on the rules of the app.
There was the idea, that combination can prevent line falling in Tomb, or the other way around, yet currently I'm not using any of that.
I'm working with the idea that the "entomb" is a phase of the 12 stages, so the line doesn't "fall", its just its state after the change.
Check The Monk posts around, there are examples of other of the 12 stages, in relation to the line.
If we view it like that, and I'm doing what I can there, then the combination doesn't have a reason to change anything, as its just the state of the line that looks like "falling in tomb".