Strange battle behavior after the July 9 patch

[Andy]

I noticed that after yesterday's patch my tank is no longer protecting the heroes behind him. Now most of the time the tank is the last hero to die; this had never happened before. Is this a bug or did they changed the way battle works?

[Revan]

Either a bug or you are going up against heroes with skills that affect multiple targets.

Horns of Hell is a mage attack that targets all enemies.
Thousand Strikes is a skill attack that does the same thing.
Sweeping Slash targets normal way but hits all enemies in the same vertical line as the target.
Piercing Thrust same as Sweeping Slash except all heroes in the same horizontal line/row are hit.