I was feeling very positive towards the Kopack Security Backpack and did my final round of research
This card could easily fit into black midrange strategies, but all of those decks have restructured around Unholy Annex since it was released in Duskmourn, House of Horrors

Alpine Grizzly Ashcoat Bear Ayula, Queen Among Bears Balduvian Bears Bear Cub Bosco, Just a Bear Copper Host Crusher Diregraf Scavenger Doc Aurlock, Grizzled Genius Dragon-Scarred Bear Drover Grizzly Druid's Familiar Duskana, the Rage Mother Evercoat Ursine Exuberant Wolfbear Fiendish Panda Forest Bear Friendly Teddy Golden Bear Goreclaw, Terror of Qal Sisma Grizzly Bears Grizzly Ghoul Hei Bai, Forest Guardian Hei Bai, Spirit of Balance Hurska Sweet-Tooth Koala-Sheep Kudo, King Among Bears Lumra, Bellow of the Woods Mother Bear Owlbear Owlbear Cub Pale Bears Phantasmal Bear Platypus-Bear Professor of Zoomancy Rampaging Yao Guai Razorclaw Bear River Bear Runeclaw Bear Ruxa, Patient Professor Spectral Bears Spirit of the Aldergard Striped Bears Studious First-Year Surrak and Goreclaw Ulvenwald Bear Ursine Fylgja Ursine Monstrosity Vastlands Scavenger Vivien's Grizzly Werebear Wilson, Refined Grizzly
How Do Arcane Spells Work in MTG