How to track who placed buff on unit?

[darkravenbest]

Im creating custom damage over time buff based on tornado slow aura, since it doesnt do any damage itself, and i use periodic event with picking all units matching condition(having this specific buff), how can i track from which unit i must address incoming damage. I must say to just pick every unit in range of this specific unit instead of using aura is not an option, because i use lingering debuff, and i need unit to receive damage even if it escapes range of aura. And another thing i must to specify, im doing it all on last pre-reforge warcraft(1.31), so if prefer method working with it.
Thank you in advance!

 

[The_Silent]

I think you have to store it in a hashtable. As far as I remember, there is no way to get the 'source' of a buff.

 

[darkravenbest]

Thank you! I will try something else then. But interesting how buffs with actual damage linked to the damage source.