How can I reverse engineering packets? (eg. packet sniffing)

[sofakng]

I'm interested in writing automation software for an online game (Magic The Gathering Online) but in order to do that I need to figure out what is being sent back/forth between the client and server. I've taken a look at the packets and apparantly they are encrypted/compressed so I have no clue what is actually being sent back and forth.

How does one go about figuring this out?

Apparantly others have figured it out because several "trading bots" exist but I can't find any websites for them...

 

[Fardringle]

Do you actually expect that anyone here would be willing to help you violate the TOS and EULA (Terms of Service and End User License Agreement) that you agree to every time you log in to the game?

Sorry, but it's not going to happen.

 

[nweaver]

the trading bots may be using web scripting based tools, such as radview.

the whole point of encrypting packets is they are secure from casual snooping/hacking.