The Wanted event is found in the Events button at the top right side of your interface. It pits you against 1 of several strong monsters, for up to 5 attacks. Basically, the Wanted monsters are test dummies that provide rewards for completing 1/3/5 attacks, an overall server wide ranking reward, and damage milestones. Shield heroes are not required for the Wanted events because the monsters don't really bite!
The tricks that I found are as follows:
Put Mason and Marshal in the front row. They both have significant damage multipliers that will apply to the folks doing damage.
Put your best 3 damage dealers in the back row.
Try to use the heroes that provide +damage for that particular monster. Which heroes types provide +damage, for that event, is found in red near the middle bottom of the Wanted event screen.
Swap your top gear to 5 heroes in the squad you are using for the event.
With my squad, I have seen about a 30% increase in damage by changing setups for the event:
From: Murphy / Williams / Kimberly / Stetmann / Morrison
To: Mason / Marshal / Kimberly / Stetmann / Morrison
