Iona and eight and a half tails

[f|i[p]]

Out of curiosity, I was wondering how Iona interacts with eight and a half tails?

If Iona is set on white then someone casts a non white spell then I use eight and a half tails to make the spell my opponent is casting white.
Does the spell fizzle or does it still push through since it was already cast?

[mujadaddy]

Iona only cares about the color as it's announced. Once on the stack, Iona can't do anything to the spell.

[Nonex]

It was already cast. The interaction between those two is basically reduced to protecting Iona from targeted removal.

[f|i[p]]

Ok thanks a lot