I have a quick question about an Astropath's Soul Binding bonus for Perils of the Warp rolls. Does he roll 2 die, designating the 10's place and the 1's place, then roll a 3rd die and let it replace either one? Or how does it work if that's not it?

Roll 2d10; roll another d10 and replace either your tens or your ones die with the third die result.