Quote Originally Posted by cally777 View Post
Hmmm, does that fit in with this?
It is an ability that he has, and even if Sin is on cooldown, if someone ever found out about DZ and Yu Yevon knew about it, he could reset the city so that no one knew about the outsider. Most likely, the intruder would be killed.

Puzzle pieces must go together.

Since the city has already been summoned, it takes no further effort to set it back to point A. He is basically running the show, the calls, and taxing for utilities. I see no reason why it would take extra effort to change something that's already running independently of the summoner, just as it takes no extra MP to keep channeling a summon in a FF game. The cost is paid, and you go on your way.