This is an absolutely ridiculous RNG grind, for something that is cosmetic only, and needs to be tweaked. If you see this item drop, go buy a lottery ticket, but try to do it indoors cause you'll probably be struck by lightning on your way outside. The Matriarch also drops a neat cosmetic item called Spider Fangs, which has about a 2% drop chance. The Matriarch has about a 1 in 20 chances of spawning, so if you see her, go buy a lottery scratcher. Either a bunch of Spiderlings, two Pot Dogs, or a Spider Matriarch. In Tomb of the Exiles, for the people who are unaware, there is a secret room you can access that can contain 1 of 3 'bosses'.