I used a rune of ascendance on Magic Dream Catcher. My understanding was that it should give me the Primalist Unique: " Dedication of an Erased Primalist", given that it’s the only Dream Catcher Unique. However, I got Gambit of an Erased Rogue instead.
Unfortunately it does not consider the specific base type, only the gear slot.
So using it on a relic will choose from the full pool of potential relic sets/uniques.
Here’s a fun tool too:
Ahh I see, thank you!