well, the whole thing about the three turtles is to maximize the chances of starting the bujin setup. 2 quilin can also help, but you really want to be sure to keep Yamato on the field. When Hare comes out, then turtle should be used at 2
As for 3 mst, I was never fond of it, but can understand its use, especially since prophecy is this deck's worst matchup
As for d prison, its either that or mirror force, depends on what you're up against, but its good to have. Also, phoenix wing wind blast is also worth some thought