are you sure, that assassin/gunners don't drop from the regular rare souls? i'm pretty sure, that i got some 3* guys from the rare souls. i have 4 gunner/assassins in my character list and i only bought one assassin/gunner soul in the beginning of my play, that's
why i think, that you can get them too from the regular rare souls.
@ dutch, don't worry we are all human. i would like to play optimal, but i also don't do it every time, since the game should also be fun and not hard work with fixed rules :-)