Quote Originally Posted by Galvuu View Post
EDIT: though honestly it's not that important because it turns out the optimal solution ends up being something along the lines of "do 4.0 if you B4 in UI" which, well, you'd obviously do anyway. Also, the 3.X rotation people compare doesn't have two spells in UI (which it must). That's part of the implied premise that Foul will always magically end up there, which isn't really the case (especially for 3.X, you're bound to run out of Fouls).
I understand that it is better to cast Foul in UI. As such I can see the merits of using 3.x rotation there so that you are not forced to use Foul in AF during 4.0 rotation or worse, lose the Foul stack. But the same thing is true for if you do too many 3.x rotations and/or don't get enough procs to extend 3.x rotation, and end up not being able to Foul in UI.