For those struggling with the invisible predator (extreme) where you need to take 3 men out by the batclaw (haven't checked if there was a simular post anywhere on this forum.
When you start, grapplehook up to the platform right in front of you. Throw a sonic batarang to left where a man is patrolling near the edge. Detonate the batarang. When three henchmen is near his body simply use the batclaw and pull all 3 of them down =) (hope it made sense:P)