How about instead of adding the 3 Nyzul sets to Magian trials for upgrading, they get upgraded by a journey up another 100 floors! Actually, probably would be reasonable to have every 5 levels above 75 equate to 5 or 10 floors. Or even a unique Magian challenge in Nyzul, like kill the randomized NM on every floor for 5 consecutive floors in 1 session (obviously would need to guarantee they pop each floor).
Somewhere out there, there is a road with 2 signs on it. One says "No Trespassing". The sign right next to it says "FREE KITTENS".