Niv-Mizzet Reborn
Legendary Creature — Dragon Avatar
Flying
When Niv-Mizzet 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.
Illustranesia
Multiverse Legends (MUL)
• #53Rulings
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.
(wotc • 2019-05-03)
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.
(wotc • 2019-05-03)
Rulings
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.
(wotc • 2019-05-03)
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.
(wotc • 2019-05-03)