An intensive pronoun is a pronoun used to add emphasis to a statement; for example,
I did it myself.
Intensive pronouns look exactly like reflexive pronouns but intensive pronouns do not have a noun function. For example, compare:
I will do it myself.
I nominated myself.
The first is intensive. The second is reflexive since it is the object of “nominated”. If you can assign one of the noun functions to it, then it is reflexive and not intensive.
αυτος is often used as an intensive; see here.