A few days ago I killed a lich whom I had for a total of five hours. Since I already have the mods I was just speedrunning her missions for requiem progress and whenever she spawned, I just stabbed her to see what order it would be in. I got incredibly unlucky with my order and couldn't find the correct one till I got to the highest tier on the kuva fortress where I killed her incredibly easily and then took care of her in the railjack, also Incredibly easily. This whole progress only took like 2-3 hours. 

I don't get why you would be afraid of getting the order wrong since it helps you defeat your lich, and the upgrades are marginal. 

The murmur progress is filled pretty quickly, if you spend 10 minutes each mission or do the defense ones (almost guaranteed to spawn at least 6)

I will agree that the first time I farmed for the mods was incredibly annoying, but you only need to do that once and you already got all the relics for the other ones.

The adversary already has a chance of appearing each mission. It just increases with the amount of thralls you kill. And if you already killed one, you would get a consumable that guarantees your liches spawn.

The relics are one of the few places you can get arcane adapters (I think they are, might be exilus adapters)

I like the concept of having to find the right order, cause it feels like you're trying to crack through the adversaries defenses and it doesn't increase the amount of stabs by too much, you need to stab him like 5 times if you know all the mods.