Is Negative Mana Steal Important On Virtuoso?

I have a vituoso with good spell stats but with -9/4 ms.
Does this make this useless?

 

I wouldn't say it's useless, since all you have to do to avoid the 9/4 ms is not use your melee attack, and you have some pretty good ids otherwise. If you plan to make a build with it, I'd advise you to focus on mana regen, so you can use spells instead of melee.

 

Thanks, that's a relief