[chucklax50]

I have been out of the loop for a ltittle while but can Dark Angels Librarians still use that physic power to force a unit to fall back and if so, if a librarian were to deep strike and use the power behind the enemy would they be cut down in ht ecrossfire rule.

 

[Corianis]

As for whether they still have the power, I do not believe that they do. But you might want to check that.
As for crossfire, it is more difficult to pull off in 4th ed, as the falling back squad can move around intervening models to impassable terrein as long as they end up closer to their baseline as when they started their move.