Official screenshot from Ubisoft.
Blade in the Crowd is for assassinating fifty enemies, any way you like.
It comes naturally through stealth play; strongholds and Templar hunts are full of targets.
Are you scared yet?
Frighten 200 enemies.
Blade from Above
Air Assassinate twenty enemies from a zipline.
Brutal
Perform 30 complete Brutal Takedowns.
Furious
Destroy twenty vehicles by ramming them.