Few things in life are for certain: death, taxes, and the Medicube Age-R Booster Pro inundating your algorithm. If you’ve found yourself on the beauty side of TikTok over the last year, chances are you’ve seen someone with glass-level skin gliding this flashlight-looking device over their cheeks, including A-listers like Kylie Jenner and Hailey Bieber. Medicube’s Age-R Booster Pro is the number one best-selling beauty device in South Korea—the birthplace of the glass skin trend, which is defined by glowing, poreless skin that’s so radiant it looks reflective. And other than being in the hands of the biggest skinfluencers and lining the shelves of K-Beauty supply stores, the device is beloved by Cosmo ’s beauty team for its ability to increase the efficacy of your skincare products while sculpting the face. So much so that it was recently crowned best skincare multi-tool in our annual Holy Grail Beauty Awards . But what exactly does this device do? And is it worthy of its viral status? And a $220 price tag?…