WAR uses a dual targetting system, everyone can have 2 different targets at the same time, one offensive and one defensive. This lets you heal one target while attacking another without having to switch targets and switch back, so it's KIND of like WoW's focus command. The /asisst targetname command sets your offensive target to whatever the targetname is attacking. The /aid targetname sets your defensive target to whatever the targetname has defensively targetted.