Three different types for Varshan (which can have terrible RNG), two for Duriel, one for moe, one for larry and another for curly. Have one type of material for summoning bosses and if anything change the quantity needed for each. One, this allows people to play the content THEY ENJOY to get them and two it is lest crap taking up inventory space which is still an issue. Not having to kill varshan and grig mulple times just to kill duriel would be a blessing as well.
The devs create too many layers to their time sinks and looking at players falling off super fast this season I think it is clear most players do not want to repeat the grind they did last season. If you want players to play longer focus on making the game enjoyable to play. Endless grinds to get mats to grind bosses you don’t need so you can grind the boss you do need drops from is just stupid. If people like helltides, they can get them there. If they like NMD, we got you covered. Like seasonal content, hey that would work as well. You are doing it for the lunar event, why not just make it the norm?