void main()

{
    effect eDamage;
    object oActor;

    // Get the creature who triggered this event.
    object oPC = GetEnteringObject();

    // Only fire for (real) PCs.
    if ( !GetIsPC(oPC)  ||  GetIsDMPossessed(oPC) )
        return;

    // Only fire once.
    if ( GetLocalInt(GetModule(), "DO_ONCE__" + GetTag(OBJECT_SELF)) )
        return;
    SetLocalInt(GetModule(), "DO_ONCE__" + GetTag(OBJECT_SELF), TRUE);

    // Cause damage.
    eDamage = EffectDamage(d6(), DAMAGE_TYPE_BLUDGEONING);
    ApplyEffectToObject(DURATION_TYPE_INSTANT, eDamage, oPC);

    // Have the PC say something.
    AssignCommand(oPC, SpeakString("You fell and took some damage!"));

    // Have "0." strike up a conversation with the PC.
    oActor = GetNearestObjectByTag("ctbmt1", oPC);
    DelayCommand(2.0, AssignCommand(oActor, ActionStartConversation(oPC)));
}