Odd behavior with Angel of Fear

I've noticed a fair amount of odd behavior with respect to Angel of Fear. Here's a battle report from playing Cast Die (Madness), using a Soldier Eddie, an Assassin Golden Son, and an Angel of Fear:

Round One: Soldier Eddie basic attacks, damages all enemies. Assassin Golden Son basic attacks, damages all enemies, kills the Possessed Mine and the Imps, but Angel of Fear passive doesn't trigger. Angel of Fear basic attacks and kills the Dice, passive triggers.

Round Two: Soldier Eddie basic attacks, damages all enemies. Angel of Fear power attacks, damages all enemies, kills the Possessed Mine, but passive doesn't trigger. Assassin Golden Son basic attacks, kills all remaining enemies, Angel of Fear passive triggers.

Round Three: Assassin Golden Son basic attacks, damages all enemies. Soldier Eddie uses Fury, damages all enemies. Angel of Fear power attacks, kills all remaining enemies, passive triggers.

You gotta kill the targeted enemy for the passive to trigger.