I would like to suggest the possibility of adding hard targeting to the game, which would allow a player to focus on an enemy target untill he choses to stop. This would allow moving without losing target and usage of ability without needing to retarget. Basically your character would automatically attack the target selected (seen at the top center of screen) and use abilities on this target if in range when you activate them without need to retarget. Loss of line of sight would obviously remove the target.

As it is, when I want to kill an enemy Regulus (small model) in a swarm of creeps late game as, say, Torch Bearer, I have to click him to start shooting (sometimes multiple times, this bug has been reported before though) if I want to shoot a fireball, I have to click / press the fireball button then target him again, and after the cast I need to retarget him for continued shooting.