Twelfth Knight: How does an ‘Impact player’ system, introduced in IPL, work?

The IPL has introduced the concept of impact player from the upcoming season.
What is that?
Apart from the playing XI, teams can bring in a substitute at any stage of the game. Teams have to name four substitutes apart from the playing XI at the toss. One of them can be brought into the XI at any time as a substitute.
How does it work?
The captain can pick one of the four substitutes as impact player at any juncture and can bring him at the start of the innings or at the end of an over or when a wicket falls. While bowling, if the team brings an impact player at the fall of a wicket in the middle of an over, he can’t be called on to bowl. And the replaced player will play no further part in the match.

Time for a New season 😃
Time for a New rule 😎
How big an “impact” will the substitute player have this edition of the #TATAIPL 🤔 pic.twitter.com/19mNntUcUW
— IndianPremierLeague (@IPL) December 2, 2022
What are the options for the batting side?
If a batting side brings on an Impact player, the batsman can replace another batsman who has been dismissed / retired. One of the players yet to come in to bat then forsakes his batting turn.
Will the number of overseas players in the XI go up?
No, that cap stays. Only 4 foreign players are allowed at any given point. So teams can bring in only Indians as Impact players unless they don’t have four overseas players in the XI.
Is there a quota for bowlers?
If player A has bowled his quota of four overs, and is substituted, the Impact player will also be allowed to bowl 4 overs. So a team can essentially use a new ball bowler in the powerplay and bring in a special for the death.