From what I've found, Nizaris must be one of the least supportable units for Egypt in MTW. Firstly Nizaris (historically) were an Ismaili sect or faction, having emerged in Egypt in 1094 in conflict with the al-Mustalim in a succession dispute for Imam. However, Nizar was assassinated, so the Nizaris fled Egypt and moved to Iran and Syria, famously setting up home in Alamut and being referred to as "hashishin" (despite the common tradition that this was due to Hasan-i-Sabah using hashish to drug his devotees, it was more a case of "they're such nutters they must be on drugs"), and were wiped out ultimately by the Mongols in 1256. In none of this history is it at all likely they would ever fight for the Egyptian "state".

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