Theyre the basis of Limited formats like Booster Draft and Sealed Deck, and theyre great for players looking to build a unique collection of cards for Constructed formats
There is a real case for Yuna's high degree of open utility here, so make of that what you will
Whenever equipped creature deals combat damage to a player, you may cast an instant or sorcery spell from your hand with mana value less than or equal to that damage without paying its mana cost
This dinosaur dragon also generates Treasure for you, providing the mana you need to cast the extra cards if you want them
And if youre really ambitious (Bontu would be proud!), you can run Phage the Untouchable, who causes any opponent she deals damage to to immediately lose the game, but be careful that she doesnt make you lose first
Ask someone to name every card type Magic has ever had