You can read the whole story below on the webpage or download the PDF.
http://us.battle.net/sc2/en/media/blizzard-comics/artanis-sacrifice/
http://media.blizzard.com/sc2/media/blizzard-comics/issue/1/en-us/artanis-sacrifice-en-us.pdf
I'm an Engineer and built the video game community Cheerful Ghost and text based mini-MMO Tale of the White Wyvern.
Cool! I like that it's free. They certainly seem to have done a lot with this new expansion for the game leading up to the release. I guess you could call these "teasers."