I'm curious to know what on him procs BFT. I usually go some AP early game for early lane bullying into a TF/Tanky for mid to late game, but a BFT could be very interesting if gotten early. Specifically I'm curious about it's interaction with his ult (I mean, if Amumu's tears procs it, wouldn't Nasus's ult work too?) and about it's interaction with his Spirit Fire. I wonder if only the initial hit of SF procs it or if the damage from walking through it does so as well.
It seems like BFT would be very beneficial to Nasus, with the CDR (super important) and the m. pen (most people never build that on him, but it would greatly help his ult damage) and just everything in general. I'll give it a try tonight and report my findings.