Indirect Targeting:For spells and combat arts, you can target through another player (usually the MT or MA). Beneficial spells will affect your target, but detrimental spells will affect your target's target. This is very useful in groups and raids to ensure everyone is on the correct target. Also known as Assisting.
To do this, target the group mate that you want to assist by right clicking an them, then select assist. Your attacks will now be on the same target as your group mate. This also works on pets.