Vertical take downs are similar to regular stealth take downs, except from above. This one will take a bit of special attention in order to get as most of the time a vertical take down wont be something that you will be thinking of. Mainly because it isn't a mechanic that a lot of games have. If there are enemies patrolling an area, find a place where you know the enemy will walk under and wait for him to get close enough for you to get the kill.
Perform 30 vertical stealth takedowns