Who is this guy you have to summons and if you do he can come in a wipe everything out or something. I use to not care if my son played this but it is really becoming an obsession.
Hey there Joe
It sounds like the guy he's talking about is something called the Wither. It's not a guy really, but a monster with three skeleton heads... you can see a picture and get more info on the Minecraft Wiki. Players summon the Wither when they want the challenge of doing battle with it, because it's hard to defeat and destroys things easily.
Hope that answers your question!