That is indeed the potential of Pako and Haldans ability to exile your opponents cards and cast them as your own
While they werent playable and did not provide any benefits to players, you could display them as decoration

Magic: The Gathering FINAL FANTASY Set Mastery 21 Magic: The Gathering FINAL FANTASY packs 5 Mastery Orbs (redeemable for card styles or sleeves in the Magic: The Gathering FINAL FANTASY Mastery Emporium) Magic: The Gathering FINAL FANTASY Mastery Pass Avatars Cloud avatar Cards and Packs 20 Packs: 4 Magic: The Gathering FINAL FANTASY 4 Tarkir: Dragonstorm 4 Aetherdrift 4 Magic: The Gathering Foundations 4 Duskmourn: House of Horror 10 Magic: The Gathering FINAL FANTASY mythic rare individual card rewards (ICRs) Level 51+: 1 uncommon ICR Card Sleeves Cloud sleeve Sephiroth exquisite sleeve Card Styles 34 Mastery Orbs (redeemable for card styles or sleeves from the Magic: The Gathering FINAL FANTASY Emporium) 15 Common card styles 10 Uncommon card styles Event Tokens 1 Player Draft token (redeemable for a Premier or Traditional Draft entry) Gold and Gems 4,000 Gold 1,200 Gems Companions 3 Chocobo companions How Many Levels Are in the Magic: The Gathering FINAL FANTASY Set Mastery

Would consider it if we have some additional large threats and need another card-advantage engine
Thats all thats going for Scarlet Spider, Ben Reilly, though never discount a creature than can take people out with commander damage in just a couple swings, especially when it only cost 2 mana
The moral of the story is that if a card is effective against two or more decks you expect to play against, its probably a good inclusion and worthy of a slot in your sideboard