Though they are designed as outer sleeves, and pair incredibly well with either a Vault X or Dragon Shield inner, they're more than able to withstand the scuffs and friction of a table and be run single-sleeved if you want
While the Extra Deck was only comprised of Fusion and Synchro Monsters at the time of the card's original Western release (it was released in 2001 in Japan, when only Fusion Monsters existed in what was then the Fusion Deck), in modern play the card could bring out a whole host of Xyz, Pendulum and Link Monsters with ease -- were it not for the card's errata
They can sacrifice themselves to put a mythical +2/+2 counter on any other chimera creature and permanently give that creature their respective ability
Handle Fresh Pulls Correctly The moment you pull a card from the pack: Touch only the edges Fingerprints on the surface show under PSAs inspection light Sleeve immediately Have penny sleeves ready before you open packs
Some were useful, such as giving the party bonuses, extra spells, or the mage actually succeeding at casting the spell they intended to