A classic one versus one battle against the Caliph from the original Stronghold Crusader. You start on a hill while the Caliph starts on the lowlands below. You have all the resources really, and can't possibly lose. Don't waste your time castle building. Assassin spam the Caliph and he will go down quickly.
You start with 6000 in gold, which is quite a lot of money for Crusader players new to Extreme. Throw down a granary, a few houses and a mercernary post and then train about 50 assassins. Caliph's base is very close which makes it even easier.
Use your arrow volley "power up" to soften up the Caliph's defending garrison, but your Assassins can probably still get the job done without it.
Estimated time to victory: 2 minutes