If any ones interested here is the final script I'm using , It works exactly the way I wanted it to. Enjoy.
/* Script generated by
Lilac Soul's NWN Script Generator, v. 2.3
For download info, please visit:
http://nwvault.ign.c...=4683&id=625   */
void main()
{
object oPC = GetItemActivator();
object oTarget;
oTarget = GetItemActivatedTarget();
object Area = GetArea(oPC);
if(!(GetIsAreaInterior(Area)))
{
ApplyEffectToObject(DURATION_TYPE_INSTANT, EffectVisualEffect(74), oTarget);
AssignCommand(oPC,ApplyEffectToObject(DURATION_TYPE_INSTANT,EffectDamage(d10() ,DAMAGE_TYPE_ELECTRICAL), oTarget));
}
else
SendMessageToPC(oPC, "This rune can only be used outdoors!");
}