Ac 2 v 40 - Arch Enemies
0Unlocked After: Sequence 6 - Memory 2: Romagna Holiday
You have two minutes to kill 10 archers. The countdown starts as soon as you kill your first archer. Purchase as many Throwing Knives as you can carry before starting this one. If you haven't already, visit a Tailor and see if they have a Throwing Knife Belt Upgrade in stock.
Once you're all suited up, head to the north end of the rooftops where the archers are all lined up, equip your Throwing Knives and climb up. Lock on to the first archer and hit him with a throwing knife to get started. A group of guards will likely start after you, but do your best to ignore them. Just continue running south across the rooftops, hitting the marked archers with Throwing Knives until you've killed all 10. - https://www.supercheats.com/guides/assassins-creed-ii/