General monster question!!!

[bluepnut]

Hello,
I just purchased my first copy of munchkin and I'm currently waiting on it to come in... I have been doing my homework by reading the rules etc. but I have a question.

When I kick down a door and the monster is a level 20 with and it has a bonus +5 to everyone (The kevinator from the guild booster pack) is he really a level 25? Or does it mean that whatever my level with my combat attributes drop 5? I am a newb so bare with me on this, the directions didn't really clarify the monsters ability affect unless I misread it somewhere. Any and all information will be useful.

Also no one around me has even heard of munchkin so I'm introducing this to my magic playing bros cause I need some change and YES I did discover this game on Wil wheatons tabletop web series.

Thanks