"Mill" is a colloquial term that originates from the card Millstone, used here to mean "putting the top cards of a player's library into his or her graveyard." For example, you could say, "In the finals of the Pro Tour Qualifier, Herbert cast Tome Scour to mill away my final five cards, dashing my chances of playing on the Pro Tour." There are many players who will play with Tome Scour in their decks
Dragonair can be obtained from Mega Shine pack in the Mega Shine set
Modern Horizons 3 has given Storm decks all the tools they need, and tons of players have been trying out the archetype, causing a bunch of cards like Ral, Monsoon Mage and Pyretic Ritual to go up in price
You can spend one mana, pull off a counter, and then Fog for the turn
A 6/6 flier that can bounce the board every turn while also putting your own creatures that give you more energy back in hand is just something that has to be dealt with
You can just as easily double all your Saprolings or Soldier tokens stats and make your token army a little more formidable as you can make your opponents Dragon army considerably less deadly (but far more adorable
