Thinking about it, I can picture the Brewers additions being Brandon Drury, David Peralta, Michael Fulmer and Dylan Floro.
Peralta is a rental, hits righties well, can be played in LF or DH. As an aging player on a D'backs team going nowhere the talent going back to Arizona would be tolerable. Plus Arizona and the Brewers have hooked up on a few deals recently.
Drury, a righty is having a career year for the Reds. A pure rental has hit much better at GABP than on the road. Plays 3B, 2B, 1B, SS and OF. The versatility the Brewers love. Again the Brewers likely wouldn't have to give up front line minor league talent for Drury.
Again the Brewers have some history in trading with Detroit at the deadline. Fulmer is another rental, strikes out just about one batter per inning, and keeps the ball in the ballpark (1HR allowed in 37 innings),
Dylan Floro maybe the costliest to acquire because he comes with an extra year of team control. He's adept at keeping the ball in the ballpark and doesn't issue a lot of walks. Maybe the Brewers could get lucky and get rid of Corey Ray as the Marlins are desperate to find a centerfielder.