Quartermaster Mathorn:
Automatic Hunting is a function that let's you automatically pick a target and continue hunting after you've killed a monster.
Automatic Hunting function includes such options as distance to target, loot pick-up and Manner Mode that prevents the character from attacking targets that other heroes are already fighting with.
During Automatic Hunting the character uses their basic Attack. If you press Alt + K, however, then drag any non-buffing skill marked with two green arrows in a circle from the Skill window to the Shortcut and click it with the right mouse button, the character will attack using the assigned skill.
Same goes for buffing skills. If you put a buffing skill to the Shortcut and click with the right mouse button, then this skill will be automatically used at the right moment.