WHich Jace are you referring too? Mind Sculptor or JVP?
In the slot, I'd look at main boarding a flusterstorm, murderous cut, toxic deluge, or snuff out. Maybe even a few other things that I'm not thinking about. It depends on if you are expecting more creatures, or more blue match-ups. If you're expecting blue match-ups, I'd throw in more counters. If you expect to see creatures, I'd bring in more kind of removal.
Did you try my updated list as much as you could?