how can i make a unit transparent?

[WC3_map_fan]

i wish to make a unit with a skill that makes it transparent (similar to dota)

except: the extent to which it is transparent depends on its helath

e.g: 100% health = 100% transparent

i can determine the rest of the leveling dont worry about that but can someone please post the trigger code? thank you so much!

 

[Dakho]

Animation - Change (Triggering unit)'s vertex coloring to (100.00%, 100.00%, 100.00%) with (Percentage life of (Triggering unit))% transparency

That's the action you'd use.