Editing WoW:Useful macros (old) (section)

=== Tank assist macros ===
 /focus [modifier:shift] target
 /target [modifier:alt] focus
 /target [nomodifier:shift/alt] targettarget

This macro sets the focus with shift-button, targets it with alt-button, and targets the target of the focus with the button itself.  Useful for DPS trying to target what the tank is targeting in a pack, or just to keep track of a polymorphed target.

'''or''':

 /focus [modifier:alt]
 /stopmacro [modifier:alt]
 /cleartarget
 /assist focus

Begin by selecting the MT/MA and then click the assist macro with the alt pressed.
If no Focus (MT/MA) has been set and the macro is clicked, you will receive a UI message stating "Unknown Unit."
If you have set your Focus and just click the macro, you will assist the MT/MA and target his or her target.