Causes the puppet to evaluate the mob's elemental resistances before choosing a spell. The puppet will not cast any spell it thinks will get resisted. The scanner does not target a mob's weaknesses, but rather avoids obvious resists. This attachment works on all offensive spells.
The puppets appear to already have a "built-in" scanner for elemental spells. This attachment is not required for choosing appropriate nukes, however, it will prevent the wrong enfeebles from being cast.
Mobs with extremely high magic resistances may cause a "bug" where the puppet stops casting offensive spells entirely. The puppet will decide that all spells will get resisted, and thus will not cast anything at all. Equipping the scanner will often cause this to happen.
The scanner may also stop silence from being cast on monsters that do not cast spells. source