We just did some testing and got some very interesting results.
  1. Aggro a mob
  2. Active Living Dead
  3. HP drops below 0 - Walking Dead is up
  4. Kill the enemy
  5. Benediction
SUCCESS

  1. Aggro a mob
  2. Active Living Dead
  3. HP drops below 0 - Walking Dead is up
  4. Have an off tank provoke the enemy and establish aggro
  5. Benediction
SUCCESS
  1. Aggro a mob
  2. Active Living Dead
  3. HP drops below 0 - Walking Dead is up
  4. Stun the enemy
  5. Benediction while enemy is stunned
FAILURE
  1. Aggro a mob
  2. Active Living Dead
  3. HP drops below 0 - Walking Dead is up
  4. Stun the enemy
  5. Have an off tank provoke the enemy and establish aggro
  6. Benediction while enemy is stunned
FAILURE

It seems whenever stun is involved, it does not work. What the hell?