Auto attacks into Mana

[Ragazar]

So im trying to figure out how to make Auto hits from heros use mana, its for a game im making that uses mana as Ammo and each auto hit will take around 5-10 mana. is there a way to do that or some trigger? (without using spells or an ability) is it even possible to happen?

 

[Clawdruid]

• Events
• Unit - A unit Is attacked
• Conditions
• Unit - Unit type of (Attacking unit) is equal to (What ever Unit)
• Actions
• Unit - Set mana of (Attacking unit) to ((Mana of (Attacking unit)) - 5.00)

 

[Dr Super Good]

Clawdruid, that works but can result in incorrect ammo reduction due to the even firing before the attack is completed.