Creatures, mostly, but Enchantments, Artifacts, Tokens, Lands, and Planeswalkers can all be Legendary
As MTG shifts towards decks that play more to the board in a tempo game, its common to see blue decks that rely on creature and permanent loops do well, using cards like Stormchaser's Talent and Quantum Riddler as blink targets and cards like Boomerang Basics as engines
A playset of everything this person had ever painted
Example: Your opponent mulligans on the play, scries to top, and plays a tapped Temple Garden
Similarly, the opponent you chose to create a copy may choose new targets for that copy as its created
I also think while you have the tools to beat it, Naya Yuna can be pretty grindy against Control