Flying
When Niv-Mizzet Reborn enters, reveal the top ten cards of your library. For each color pair, choose a card that’s exactly those colors from among them. Put the chosen cards into your hand and the rest on the bottom of your library in a random order.
A "color pair" is exactly two colors. There are ten color pairs in Magic: white-blue, white-black, blue-black, blue-red, black-red, black-green, red-green, red-white, green-white, and green-blue.
03-05-2019
wotc
If the top ten cards of your library don't contain all ten color pairs, you choose as many cards as you can and put those cards into your hand.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.