code\:

int GetExistItemInInventory(object oTarget, string sItemTag)
{
   object oItem;
   oItem = GetFirstItemInInventory(oTarget);
   for( ; ; )
   {
     if (oItem == OBJECT_INVALID)
     {
       break;
     }
     else
     {
        if (GetTag(oItem)==sItemTag) return TRUE;
     }
     oItem = GetNextItemInInventory(oTarget);
   }
   return FALSE;
}
void ApplyVisualEffectsToMagicDoor(int MagicDoorType)
{
   // apply visual effect to door (depends on MAGIC_DOOR_TYPE)
    effect e1,e2;
    if ((MagicDoorType<0)||(MagicDoorType>2)) MagicDoorType=0;
    switch(MagicDoorType)
    {
      case 0:
            e1 =  EffectVisualEffect(VFX_DUR_AURA_SILENCE);
            e2 =  EffectVisualEffect(VFX_DUR_LIGHT_WHITE_5);
            break;
      case 1:
            e1 =  EffectVisualEffect(VFX_DUR_AURA_COLD);
            e2 =  EffectVisualEffect(VFX_DUR_LIGHT_BLUE_5);
            break;
      case 2:
            e1 =  EffectVisualEffect(VFX_DUR_AURA_FIRE);
            e2 =  EffectVisualEffect(VFX_DUR_LIGHT_RED_5);
           break;
    }
    ApplyEffectToObject(DURATION_TYPE_PERMANENT,e1,OBJECT_SELF,1.0);
    ApplyEffectToObject(DURATION_TYPE_PERMANENT,e2,OBJECT_SELF,1.0);
}

void ActionMagicDoor(float MaxDistance,int MagicDoorType,string ItemTag)
{

    // get distance to player
    object oPC = GetNearestCreature(CREATURE_TYPE_PLAYER_CHAR,PLAYER_CHAR_IS_PC);
    float distance = GetDistanceToObject(oPC);
    if (distance < MaxDistance )
    {
        // -> player is in near enaugh
        if ((GetExistItemInInventory(oPC,ItemTag)==TRUE)||(MagicDoorType==0))
        {
          // -> player can pass
          if (GetIsOpen(OBJECT_SELF)==FALSE)
          {
            ActionPlayAnimation(ANIMATION_PLACEABLE_OPEN);
            ActionOpenDoor(OBJECT_SELF);
          }
        }
        else
        {
          // -> player can not pass
          if (MagicDoorType==2)
          {
            //-> do bad things to player (one time)
            int iDidDamage = GetLocalInt(OBJECT_SELF,"DidDamage");
            if (iDidDamage == 0)
            {
              AssignCommand(oPC,ActionCastSpellAtObject(SPELL_SOUND_BURST,  oPC,METAMAGIC_MAXIMIZE,TRUE,FEAT_FIRE_DOMAIN_POWER,PROJECTILE_PATH_TYPE_
DEFAULT,TRUE));
              // 25% damage
              int dm = GetMaxHitPoints(oPC) / 4;
              effect md = EffectDamage(dm,DAMAGE_TYPE_MAGICAL,DAMAGE_POWER_NORMAL);
              ApplyEffectToObject(DURATION_TYPE_INSTANT,md,oPC,1.0);
              iDidDamage = 1;
              SetLocalInt(OBJECT_SELF,"DidDamage",iDidDamage);
            }

          }
        }
    }
    else
    {
        // -> player is to far away
        if (GetIsOpen(OBJECT_SELF)==TRUE)
        {
          ActionPlayAnimation(ANIMATION_PLACEABLE_CLOSE);
          ActionCloseDoor(OBJECT_SELF);
        }
        SetLocalInt(OBJECT_SELF,"DidDamage",0);
    }
}
void main()
{
    // Settings:
    float MAX_DISTANCE = 4.0;                 // max. distance to doo
    int MAGIC_DOOR_TYPE = 2 ;                  // 0 ... simple magic door (no item required)
                                              // 1 ... normal magic door (item required)
                                              // 2 ... evil magic door (item required, if no item found -> spell cast on player)
    string ITEM_TAG = "DazursWegbereiter";    // ItemTag of Item to open the door

    ApplyVisualEffectsToMagicDoor(MAGIC_DOOR_TYPE);

    ActionMagicDoor(MAX_DISTANCE,MAGIC_DOOR_TYPE,ITEM_TAG);

    DelayCommand(2.0,ActionMagicDoor(MAX_DISTANCE,MAGIC_DOOR_TYPE,ITEM_TAG));
    DelayCommand(4.0,ActionMagicDoor(MAX_DISTANCE,MAGIC_DOOR_TYPE,ITEM_TAG));
}

code\:

int GetExistItemInInventory(object oTarget, string sItemTag)
{
   object oItem = GetObjectByTag(sItemTag);
   if(GetIsObjectValid(oItem))
   {
      object oPosessor = GetItemPossessor(oItem);
      if(GetIsObjectValid(oPosessor) && (oPosessor == oTarget))
          return true;
      else return false;
   }