With Super Polymerization another ever-present threat in the metagame, Fusion summoning is a mechanic that grants decks that can take advantage of these cards to some of the most powerful cards in the game, including Destiny HERO - Destroyer Phoenix Enforcer and Guardian Chimera
*Select 1 Spirit monster on the field
There's also extra value delving into other colors, and in flexible collect evidence spells like Urgent Necropsy
These aren't the only valuable cards you'll want to crack open, however
Once it's on the Battlefield, it can be interacted with by anything which targets a Permanent, including something old-school, like Desert Twister, or more modern, like Aether Helix
Double-sleeving tips Use a perfect fit (top- or side-loader) first, then a matte or glossy outer