I rarely use the mb fireball into trait set up unless I have a massive life lead and feel like laming my opponent out, trait zoning is easy for most of the cast to at least avoid if they play patiently which a good Flash usually will and meter gain isn't that great outside of on block. I find this MU heavily in his favour.
I think sometimes we can confuse the fact that our opponents have little if any experience against Zatanna with a MU being even or maybe in our favour. @
Rodrigue what are your thoughts on this MU?