DamageThing — damages the actor that triggered the special.
DamageThing (damage);
DamageThing ( damage // How much to hurt the activator );
This special's function is the same whether you activate it on a line or use it in a script. However, it cannot be used in open scripts because open scripts are triggered by the world and not by a specific actor.
DamageThing hurts whatever activated it. It cannot be used to damage random actors on the map. Use Thing_Damage if you want to damage actors with a particular TID.
A negative damage will heal the activator, but it's better to use HealThing for this purpose, because it offers more control over the healing process.
If the activator is a player and you use a positive damage, any armor the player has will decrease the actual amount of damage dealt. On the easiest skill level, players also take half damage. Monsters will still take the full amount of damage specified.
If you use DamageThing in a script, any damage of 10000 or higher will result in a kill, just as if you had used a damage of 0.
Take away 10 points of the activator's health:
DamageThing (10);
Kill the activator:
DamageThing (0);
Hexen