Rift = Rounding
I think a precise rounding chisel could work well. Each whack takes off a corner like a precise bevel does.
Maybe not 8 corners to make a sphere. But put eight blocks together and whack 7 corners off each to form a sphere (sort of like bevel chisel gleam “gems” at Ult Finata and other places)
I would propose a special case that you stack lucent and gem chisels together though. I already have too many chisel stacks.