Is the Iron Curtain achievement in Assassin's Creed: Revelations getting you down? Well here, have an easier one to try out. The 'Mosh Pit' calls for ten guards to be poisoned at the same time. Do that, and you'll net a cool 20G on Xbox 360, or a bronze trophy on PlayStation 3.
The best way to do this, is to launch a few datura bombs from up high. But you can't just find datura bombs lying around. That'd make too much sense, so you're forced to craft them. Gather your ingredients, and get to poisoning guards!