Its a USPSA (practical shooting/action pistol) match put on by MPPL. The Monster Match usually has a higher round count than the normal monthly or twice monthly USPSA matches that MPPL hosts. If I remember correctly, the past years, the Monster Match was shot over 2 days, which meant that you could shoot 2 different divisions, using 2 different handguns. I can't remember if the scores were combined for the final score or if they were scored as different divisions. This year its going to be a one day, one gun match. It sounds kinda like how this years Aloha State Games match was run. These "bigger matches" typically have more involved stages, more targets, good amount of movers, and steel. All of their matches are fun and challenging though.
Shoot them an email if you're interested, they're usually more than happy to provide the info you need and respond fairly quickly. Hope this helped a little.