+2 DC if several items present at casting are removed.
+5 DC to identify individual spells if there has been significant rearranging of items since time of casting.
+5 DC to identify individual spells for every additional spell’s residue cast within two Halflife Periods (one spell may interfere with the other but not vice versa).
+6 DC if investigating a person-sized object’s residue.
+12 DC if investigating a small item’s residue.