Whilst you do need to meet the requirement of having three legendary creatures on your side of the battlefield, this requirement is actually a bit easier to meet than it sounds because Kolvori herself counts towards that, meaning you only need two additional legendary creatures by her side
Cinderella - Ballroom Sensation Lorcana Card Get a detailed overview of Cinderella - Ballroom Sensation, including recent decklists, prices, stats, and more
It gives you a creature you can attack with, ramp with or use to half-assed-last-gasp and thats pretty sweet
Only time will tell if the unique draw of Bucky - Squirrel Squeak Tutor is enough to override its current lack of rarity, and as usual, it's better to simply enjoy the game than to invest heavily in speculative purchases
Use the number of creatures you control and the number of Equipment you control when Slash of Light resolves to determine how much damage is dealt