starting in the 7th inning they introduce the powerball. Its a red baseball with white seams and if that ball is put in play then however many runs score its a 4x multiplier. solo hr basically just became a grand slam. sac fly scores...you guessed it, 4 runs. base on balls...means you take 4 bases BAM thats at least 1 run maybe more.
Pretty much when the powerball is in play you want the batter to either foul it out of play or hit a lazy popup that does not advance the runner. If the batter strikes out on the powerball then no matter how many outs there are that's automatically the end of the inning. The only exception is that in the NL you cannot use the powerball when the pitcher is up (this is assuming the NL goes back to pitchers having to bat, they might keep the DH from now on who knows?)
Oh and obviously once the powerball makes contact w/ the bat - either a foul ball or put in play, then that's the end of the powerball for that half of the inning.