What's the Name of That Book??? discussion

I read a series of books in 6th grade 1994, I am assuming it was written before the 90's because it was a series of more than six books. The main character was a young man who traveled to alternate dimensions. He had a friend who had green skin. He found a young dragon in one of the books that considered him his pet. He made his home with his friends in a dimension where travelers from many other dimensions visited. In one of the books they traveled to a world full of vampires. He was introduced to a complex card game where the rules changed depending on the day of the week and other variables. I think one of the books showed the boy and his friends on the cover, I remember the green skinned monster with pointed ears. I have been wracking my brain to figure out the name of this series not only because I want to finish it, but I have a child that runs through books like water.

I figured it out myself, it was the Myth Adventures.