Round table

I'm sorry, but in my opinion, this is nonsense.

It depends on how you understand the term "damage"... If it refers to the result of an attack (casting a damaging spell, etc.), then it's not nonsense at all. In the case of resistance, the result is zero. Furthermore, you must consider that the opponent may have resistance, i.e., it's not a secret to you that the possible result of a spell cast is not the only one.