I've been maining scorpion and using his death spin + spear buff moves, and wow death spin is a terrible move, it serves almost no purpose aside from anti air, and maybe chipping out with the spear buff with it.
Yeah, that is all I've used it for too. Anti-air and chip damage when amplified to kill the opponent. I have also found it as a good keep away move as well. I don't think it should be worth 2 slots though as someone mentioned it was. I used it to apply pressure at the end of a round if the opponent's health is low.
I did like the string they added to the Chain reaction variation too. I found it to be a good mix up and also as a good footsie tool only at mid-range though. I managed to beat a really good Kabal several times with it online. However, it can't be overused as it becomes too predictable like anything else.