Batman: Arkham Asylum
47 Achievements
1000
20-25h
Invisible Predator
Complete one predator challenge by using only Silent Takedowns and without being detected
10
How to unlock the Invisible Predator achievement in Batman: Arkham Asylum - Definitive Guide
Combatting, DISCOKING
Can easily be done on the first predator room "Silent Knight". Simply take down all the enemies using Silent Takedowns 
from behind.
For a visual walkthrough, see the following video:
Fizzmatix
to sneak up behind enemies. Press 
to perform a silent takedown; once you have killed the enemy you are after, make a quick escape to one of the gargoyles or another section of the map.Using other weapons or takedown tactics will cause you to miss out on this achievement, so make sure you don't use the Batarang, Batclaw, or glide takedowns.
Fizzmatix
This is a lot easier than it sounds, pick on of the earn stealth challenges. You will want to take your time don't rush this as you may get caught. Drop down and hold the to sneak up behind enemies. Press to perform a silent takedown, once you have killed the enemy your after make a quick escape to one of the gargoyles or another section of the map.
Using other weapons or takedown tactics will cause you to miss out on this achievement so make sure you don't use the Batarang, Batclaw or glide takedowns.
Fizzmatix
to sneak up behind enemies. Press to perform a silent takedown, once you have killed the enemy your after make a quick escape to one of the gargoyles or another section of the map.Using other weapons or takedown tactics will cause you to miss out on this achievement so make sure you don't use the Batarang, Batclaw or glide takedowns.