there was no check to use it with, was a simple spell cast. Right now the dot is on one of 3 planets that have been named in novels in the outreaches of the setting heh
that is what it was
https://www.d20srd.org/srd/epic/monsters/umbralBlot.htm but its a remake of something even more scary, a immortal Blackball that is what Theo thought it was
http://creaturespotlight.blogspot.com/2015/02/blackball.html love this in the official write of the MM: Disintegrate: Any magical or non-magical object or person who simply touches the Blackball is destroyed. There is no saving throw. You are dead. Your items are gone. Life sucks.