Matryoshka Shell?

While walking around Iboju village I walk into a random house to find myself fighting something called "Matryoshka Idol." After defeating its ten stages, and identifying it, I get a chestplate called "Matryoshka Shell." I find it surprising to have 20 powder slots, but still confused as to what it could be used for. I planned on just throwing it away, but I find it hard to do that with its 20 powder slots. Could anyone tell me what to do with it? Thanks.

 

It's quite strong for elemental defense, I think it beats all except Gravity when fully powdered (though at a cost of about 40 LE to powder that much). Even so, it's got plenty to elemental defense for its level even without powders - if you're going rainbow, it's a good tank item until you get access to Admiral (you can powder it with tier 3s for cheap and still get a solid ~80 rainbow elemental defense). The walkspeed and lootbonus are also quite nice. I personally have never used it in playthroughs since I tend toward glassier high-damage builds while leveling, but it's a good option.