ASSIST

Syntax: assist <player name>

Assisting someone will cause you to start fighting the same monster or
player that person is currently fighting.

Syntax: autoassist

Using autoassist will allow your character to automatically assist the
leader of the formation in a fight. This is similar to ASSIST but in this
case, your character will do it without prompt. You are able to turn this
on and off with only the AUTOASSIST command.