Alter Aeon Online Help

Keywords are:  'autoassist assist'

The autoassist command is provided to help players in groups.  Often
in the heat of battle, it can be difficult to tell who to assist next.
When autoassist is enabled, you will automatically switch targets if
your current target is defeated.

[Experienced players - this behavior is similar to that of the berserk
skill, where you automatically start fighting another target until
nothing is left standing.]

WARNING - The autoassist command is not a true autoassist.  You will
only autoassist if the mob you are fighting dies, but others in your
group are still in combat.

Autoassist will not cause you to automatically assist at the start
of a battle.  You must manually assist at the beginning of combat.

Fortunately, the shortcut 'a' (the 'assist' command with no
arguments) can be used for that purpose.