Making units damage upon death
Making a unit deal damage on death is something that is done by using the Data Editor (versus the Trigger Editor). It is not quite as simple as making a straight duplicate from the Baneling's, and in fact, the Baneling seems to have a lot of "fatty" data attached to it, that in most cases the user will not require. This article shows how to create a damage-on-death behavior at its bare minimum.
Hopefully, you're at this article to improve it; however, you're probably here because you're trying to make a unit deal damage on death but you are either getting nowhere or are stuck with a unit dealing no damage. If you're one of the latter groups, I hope that this article can relieve much stress from you.
What follows is the steps taken to make a unit deal damage on death to its surrounding area at its bare bones.
To begin, search for "Baneling - Explode" in the Behavior tab of the Data Editor and open up the Duplicate dialog for it.
Find and select Baneling - Suicide (Remove Buff), Baneling - Volatile Burst (Set), Baneling - Volatile Burst (Unit Damage). Afterwards, hit "OK".
From here on, the copied data entries will be referred with the prefix "Custom" (versus "Baneling"). Furthermore, the Object Explorer will be extremely useful, so make sure it is open.
Modifying the Behavior/Effect Data
Select Custom - Volatile Burst (Set) and modify the Effect - Effects field so that the only entries are Custom - Suicide (Remove Buff), Custom - Volatile Burst (Unit Damage), and Suicide.
Confirm your changes. Your Object Explorer should refresh and now show a smaller list of Effects.
Now, perhaps the most important step, that is also, coincidentally, probably the most frustrating one when the user is not aware of it, is to select Custom - Suicide (Remove Buff) and modify the Behavior - Behaviors field from Baneling - Explode to Custom - Explode.
WARNING: Without this change, the unit with the Custom - Explosion behavior cannot deal damage on death.
Note: the Effect Suicide does not appear to be necessary in making a unit deal damage on death.
The last step is to modify the actual damage aspect of making a unit deal damage on death.
Select Custom - Volatile Burst (Unit Damage).
The aspects here that you probably want to modify are in Combat - (Amount, Attribute Bonus) and Effect - Death, Search - (Area +, Search Filters).
For making a bare minimum damage-on-death behavior with most values left default, the only change that the user probably want to make is in Search - Search Filters; that is, the search filter should be modified to "Allow" structures (versus "Require").
Confirm your changes.
Giving the Unit the Behavior
To complete the changes, find the unit that will deal damage on death and modify the Behavior - Behaviors + field to include Custom - Explode.
Confirm your changes.
Congratulations, your unit will now deal damage on death.
- Taken from an original article written by New-Hydrolisk (Staredit.net)