Summoning Singular Creatures

I just ran across what I believe was a singular Lich Priest (Blue fire-orb instead of yellow). I grabbed its core, managed to make my way through the rest of the realm, and now I don’t see anything at the summoning Brazier… just normal ol’ Lich Priest. 8 normal cores, and nothing suggesting there’s any other Lich type to be summoned. I’ve played 45 hours, and this is the first singular creature I’ve encountered… did I manage to botch it up? Or is there some other way of summoning Singulars that I’m not aware of?

if it was a singular then in summoning interface you ll have 2 strings to summon lich priest
like
[Lich] Lich Priest
[Lich] Lich Priest
one of those will be about your 8 normal cores
another one about 1 singular core
Also iirc in your items/cores singular cores should have the prefix.
Im not 100% sure how its now since last singular i got more then 150 hours of playtime ago.