Could someone explain to me the rules of a 4 Ball Ambrose Las Vegas Event?

Not sure if this is it ? We call it ambrose, they call it scramble in the US. Sounds like an interesting version on Ambrose however I reckon it might add an hour to the round.

The Las Vegas Scramble is a variation of a regular scramble that involves the use of a 6-sided die. Here’s how it works:
Before play begins, assign a number from one to four to each member of your 4-person team. At each tee, all four members tee off, then the 6-sided die is thrown or rolled. Check the number that comes up on the die. If it is a 1, 2, 3 or 4, then the drive of the team member whose number matches must be used on that hole. (Example: On the first hole, all four team members hit drives. Then the number 3 is rolled. The drive hit by the team member who is designated No. 3 is the drive that must be played on this hole.)

If the die comes up 5 or 6, then the team can choose the best drive among the four.

Whether the die chooses your drive for you (rolling 1 through 4), or allows the team to choose the next drive (rolling 5 or 6), the hole is then played out as a normal scramble.

There is a lot of luck involved in a Las Vegas Scramble. The key point to remember is that the die is rolled only after each player has hit his drive.

Sounds like a pain to me!