Teemu
Hero
Take a look at this:
What exactly happens when a 'creature with an Intelligence score of 12 or higher' notices the sensor with a DC 20 Int check? How do they notice it? Do they see something? Wouldn't that be a Wis (or Spot) check? Do they 'sense' something? How do you explain that 'Int 12 or higher'?3.5 SRD said:Scrying
A scrying spell creates an invisible magical sensor that sends you information. Unless noted otherwise, the sensor has the same powers of sensory acuity that you possess. This level of acuity includes any spells or effects that target you, but not spells or effects that emanate from you. However, the sensor is treated as a separate, independent sensory organ of yours, and thus it functions normally even if you have been blinded, deafened, or otherwise suffered sensory impairment.
Any creature with an Intelligence score of 12 or higher can notice the sensor by making a DC 20 Intelligence check. The sensor can be dispelled as if it were an active spell.