We've heard that Blizzard's hugely anticipated Diablo 3 will have an immensely challenging final difficulty level
and it looks like the StarCraft 2 team are not going to be outdone, with the announcement of a "fiendish" new official Custom Game modification called StarCraft Master, due in the "next few days" and aimed at teaching newcomers some of the advanced play techniques that can be used in multiplayer.
In a blog post on the official site, Blizzard describes the new addition:
A new challenge is coming: the new single-player Blizzard mod StarCraft Master. StarCraft Master offers you the opportunity to put your skills to the test in 30 different challenges that will tax your knowledge and your ability to control your forces. Each fiendish challenge will demand your utmost concentration to prevail, and they’ll help you hone your unit micro-management skills in situations which mimic real battles.
for more specifics and keep an eye on the "Custom Game" menu over the next few days.