You will need to create a bomb that spreads poison for this achievement. To make the bomb, you must have ingredients to create it. Any shell works technically, but impact is best. Use the British Gunpowder to ensure widest area of effect. The main ingredient to even make the bomb is Datura Powder. You can get these ingredients in many ways, looting dead bodies, chests, rewards, etc. You can even just go buy them if you can't manage to make them.
Focus on crafting both a Cherry Bomb and a Datura Bomb (the poison bomb's name). Find an area with a lot of guards and throw a Cherry Bomb in the center. You may also use other forms of distraction based bombs as well. Of course, there are other ways but the ones listed will make it easier.
An excellent spot to get this is in Sequence 4 Memory 1. You'll come to a courtyard after knocking out 6/9 people and there will be several guards. Make sure you have a Cherry Bomb. Climb up a little bit or stay out of view. Throw a Cherry Bomb to get the guards to one spot. Now throw your Poison Bomb in the center of them to gain the achievement.
Throw a bomb that taunts guards, like the acoustic one, wait, throw a poison-bomb. This can be easyly done in sequence 3, last mission (free your 2 assassins) Throw the 2 bombs from one of the roofs near the first assassin. This may take some time/attempts.
@ #6 This is the first I'm hearing of a poison bomb, sounds interesting...I was starting to think I was going to have to pull some Houdini shit with a smoke bomb along with projectile poison darts and poison blade combos.
it's easly done in sequence 4 mission 1(the one where you beat up the minstrels), just get up to the 1st set, and there should be at least 20 guards to your right, just throw a cherry bomb and when they all get together throw a poison bomb with british type powder (for the biggest area of effect)
Definitely agree with #8. Once you arrive at the first spot, head up the tower on the right and throw a cherry bomb at the group of guards near the tent in the middle. Once two groups huddle around, throw a poison bomb, then throw a second one when the third and fourth group come over. Can easily poison around 15-20 or so at a time.. hilarious!
Super Easy. I did it on the mission where you kill the Janissary Captain. Just threw a couple poison bombs into the area with all the guards and then air assassinated him for !00% synch. Fun and hilarious to watch. lol
Took me two tries, but I got it at the Janny camp. Climb to the highest point of the broken part of the wall on the eastern side of the camp. Throw a cherry bomb as close to the guys guarding the far southern entrance to the camp (in between the tents), and just for good measure throw another one just a little left of that (to pull in guards further from the north), then get your poison bomb ready. Right when the last of the guards are getting ready to enter the kill radius of the bomb, toss it. Good luck.
Aside from the camp, here's another spot. It's the restricted area NE of Hagia Sofia (use the tunnel warp if you don't know where that is). It's Topkapi Palace. The guards will immediately attack after the initial suspicion mode. In the open courtyard there are three groups of four guards, and luckily none of them are "agile" class so they can't outrun you (which sux when you're trying to group mobs together). Just cluster them all and throw a Datura bomb with impact shell and british gunpowder. Do this again with any straglers until the cheevo pops. This is also a great place for the "I can see you..." cheevo.
I did it at Fatih Camii. There are 8 guards in the courtyard and 4 right outside the door. I stood where I could see all 12 and threw a cherry bomb in the courtyard to draw the 8 together and while they were walking towards that bomb, I threw the poison bomb at the 4 guards at the door then quickly turned and threw another at the 8 guards.