Isshin, Two Heavens as One's ability affects only triggered abilities with conditions that are directly related to attacking, such as "whenever [this creature] attacks" or "whenever you attack with one or more creatures." It does not affect triggered abilities with other trigger conditions, such as "whenever [this creature] becomes tapped." Isshin's effect doesn't copy the triggered ability
As it stands today, Diablo is essentially the only character with the alternate shift mechanic being used commonly in the game
This variety of characters ensures that every player will find something to enjoy
Then you can get a Propaganda for two rounds and then make a bunch of Treasures on the way out being equal to your larger size power your foes' have
As it is, however, it probably will just get removed as opposed to causing any hinderance to foes
Thats because the way the triggers are worded, you can put the last chapter ability on the stack, and then remove a counter to keep the Saga but get the last effect on the card