In any macro you have to put the highest priority action first.
Code:
/cast [mod:alt,@player][@mouseover,exists,help,nodead][] Lesser Healing Wave
The macro will be executed as follows:
- Check if alt is pressed, if it is, cast at player
- Check if you're hovering a friendly unit that's not dead,cast at him
- Finally, just behave as normal spell if both previous conditions aren't met
edit: It's a newer macro formatting I've depicted here. The older syntax equivalent macro would be this:
Code:
/cast [modifier:alt,target=player][target=mouseover,exists,help,nodead] Lesser Healing Wave;Lesser Healing Wave
However I'd suggest sticking to a newer (shorter and "sexier") format.