World of Warcraft Classic
/cast [mod:alt,@player][@mouseover,help,nodead][help][@targettarget,help,nodead] SPELL
This macro is the basis of all your healing and buff spell macros. Replace SPELL with the spell you want to cast on a friendly unit, including healing spells and dispels. This macro has several functionalities: if you're holding Alt, it will self-cast; if you're hovering over a friendly unit, it will cast on them; if you have a friendly target, it will cast on them; if your target is an enemy targeting a friendly unit, it will cast on the enemy's target. Finally, if none of the above conditions apply, it will cast as if there was no macro, and generate the tooltip.