Q. If calling upon anyone other than Allah (swt) is not allowed then what is “Nad e Ali”?
Nade Ali is not mentioned in even a single hadith, rather it is only mentioned as a poem in later books. The earliest source for it is Shaikh al Kaf’ami (d. 905 AH), who mentioned it in his book “Misbah” claiming that he saw a handwritten note from Shahid al Awwal saying that this poem (i.e. nade ali) should be recited for difficulties. The latter scholars who quoted it from Kaf’ami (such as Allamah Majlisi, Muhadith Noori and Ayatullah Ali Namazi Shahroodi) also made it clear that it is only a poem, not a hadith.
Akhbari scholars, like usooli scholars, are not a homogenous group, and thus had different views. The strict akhbaris like Shaikh Hurr al Amili believed in doing tawassul only as per what’s mentioned in ahadith from reliable books like kutub al arba (hence no nade ali, dua tawassul etc for him). There is no concrete evidence to suggest that Nade Ali or Dua Tawassul even existed in the times of classical scholars like Shaikh Kulaini, Saduq, Tusi, and Mufid etc, and so there is no way we can attribute them to the Imams of the Ahlul Bayt (as).