NPC Code:
if (playerchats) {
setstring client.shield,#2;
if (!strequals(thelevelwhereyoucansetshield,#L)&&star tswith(setshield,#c)) {
setplayerprop #c,Shield setting is disabled in overworld;
setplayerprop #2,#s(client.shield);
}
}
one way to do it.