@Tizzy
First, it was Ramses’ Place.
If it was true that Exador had vissited it many times, then he should have not not assesed the design on the floor (he did to see if it was some sort of magical trap), or take much interest of the carvings.
Also, Exador doesn’t seem to stay that much in the Abyss. Not to mention he is in a potential enemy territory so he should have been more vigilant and take notice of such things.