This talent is strongest when used with Frost Trap, as each "pulse" of the trap's effect can trigger entrapment and they occur once per second. Previously, this meant that once the target became entrapped, they would likely remain entrapped for the entire duration of the Frost Trap. However, Entrapment is now affected by diminishing returns. This still means that a frost trap will generally entrap a foe for 7 seconds instead of 4.
Edit
Patch 3.2.0 (2009-08-04): This talent no longer works with Immolation Trap or Explosive Trap. 
