Damage over time

Trigger based damage over time?

I wanted to make a spell that is based off Banish, but at the same time damages the unit that is targeted, anyone know how to make DOT damage on the unit? Got this so far...:P

Turn to Smoke
Events
Unit - A unit Begins casting an ability
Conditions
(Ability being cast) Equal to Banish
Actions


I need the actions based on that...or if you know a better way, please let me know :)

Ok, some more ideas have just poped into my head :P

Here is what I would like to do:

When the spell Turn to Smoke is cast, the unit begins to take damage for the duration of the spell.

In addition, the hero can Enter the plane of Smoke, and attack the unit. I was thinking about making the unit invulnerable and making the heroes attack to only attack invulnerable. (if I set both invuln and organic, will the hero only attack thoes that are invuln and organic, or both types?)

But I can't seem to figure this one out...

Anyone have any ideas?

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