For damage prevention, I would use data. You could use a behavior, use the damage response to reduce all damage to 0 and add the dark templar's damage effect to the exception list for the damage response.
If you not only want to prevent damage, but also prevent everything except dark templars from targeting the overmind, you can set the overminds invulnerable flag and enable the dark templar weapon to attack invulnerable targets.
I'm doing remake of Broodwar Zerg mission8 and I need help with main objective.
Only Dark Templars can deal damage to Overmind.
What is best solution to allow only Dark Templars to attack the Overmind?
I have made Overmind invulnerable by triggers.
Should I use data or triggers?
For damage prevention, I would use data. You could use a behavior, use the damage response to reduce all damage to 0 and add the dark templar's damage effect to the exception list for the damage response.
If you not only want to prevent damage, but also prevent everything except dark templars from targeting the overmind, you can set the overminds invulnerable flag and enable the dark templar weapon to attack invulnerable targets.
Found solution.
Weapon: Target Filters, allow invulnerable