I use both sever and reap yet watching the buff number for Blight it doesn’t go up as fast as the tooltip says it SHOULD, seemingly taking more than 2 seconds to apply another stack for the 10 stack bonus. One would ASSUME that using sever SHOULD put 2 stacks of blight on a target if you do it right but no, it really doesn’t seem to follow the tooltip at all.
It’s like the 2 second blight timer is what screws it all up, DESPITE the fact the tip says ANY source of shadow damage should add to the stack.