[aspo]

I just got the game and have been playing a lot of test games. One time I noticed a magic site that had an enter site option. Unfortunately I quit that game before trying that and I haven't seen any sites like that since. So I have a few questions.

What does entering a site do?
Can any commander enter a site?
How do I know a site is enterable?

Also is there a list of what every magic site gives you and how hard they are to find? Are there any sites that do any more than just give a set number of gems?

Thanks.