I read all the comments about this mob and decided to try Watering Hole.
The location where everyone said the PH would be a rat had a discordling standing there.
I killed it a few times (20 min respawn) and no signet mob so after one kill I decided to look around to see if the PH cave rat was somewhere else.
Well, I found the actual signet mob in the room at the very end of the map, at the southern most point. Loc -460, 370
There was a girplan roamer in the hall and a static dragorn in his room.
Killed him and he dropped 6 signets.
I cant be sure he is up on zone creation, but he was for me this time. Easy kill for 70 ENC, 70 Wiz box, 70 NEC box