For the achievement Mosh Pit, I have to poison 10 guards at once. I attempted this last night by breaching the palace walls and having 3 sets of Janissaries attack me at the same time. Despite flinging Desura bombs as if they were full of candy, I didn't manage to get 10 of the poisoned at once.
One of the other achievements also requires that I have a group of 5 guards injured by caltrops and then scaffold'ed, which seems somewhat similar in that I need a whole mess of guards in a relatively confined space.
What's a good way to get a whole bunch of guards together, and what's the best way to get them all poisoned at once?