Vou can use a smartbomb for that or use the scripted version I use on my mod.
void damage_all_enemies(int damage, int drop, void atk_type, void vName, char sound)
//thanks Lagarto, Piccolo and White Dragon
{
int iEntity;
void vEntity;
void self = getlocalvar("self");
int iMax = openborvariant("count_entities");
playSound("data/sounds/"+sound);
for(iEntity=0; iEntity<iMax; iEntity++)
{
vEntity = getentity(iEntity);
float x = getentityproperty(vEntity, "x") - openborvariant("xpos");
float a = getentityproperty(vEntity, "a");
float z = getentityproperty(vEntity, "z");
void Spawn;
if(getentityproperty(vEntity, "type")==openborconstant("TYPE_enemy"))
{
clearspawnentry();
setspawnentry("name", vName);
setspawnentry("coords", x, z+1, a+30);
spawn();
clearspawnentry();
damageentity(vEntity,self,damage,drop,openborconstant(atk_type));
}
}
}