Failed objective has weird wording, so lets exploit that!
Failed Objective play as: Discard all Evil Characters in battle. Protect Lost Souls from rescue by Heroes this turn.
Note that you don't have to discard the evil characters to protect lost souls. And wouldn't you look at that, Four Squads of Four, a character with very low numbers, heals himself the first time he is discarded!
Play as: If this character is discarded, heal it. Limit once. Protect Lost Souls in N.T. silver Sites from rescue by humans. May band to Four Squads of Four.
Throw 4 of these guys and 4 failed objectives in a t2 an you've got chump blocks for days!
Alternative combos to exploit Failed objective would be with Wolves in Sheep's clothing and using a gold heretic or using a character that is protected from all discard abilities. I like the heal method better than the protect because then your opponent has a chance to negate Failed Objective.