Dimir and Izzet builds lend well to drawing more cards, and the flash gives you an element of protection and surprise
Its extremely easy to cast this spell and get it to Level 2 in the same turn if youve been banking Treasures
Mana Drain One of the most iconic counterspells in Magics history, Mana Drain not only nullifies a spell but also provides you with mana equal to the countered spells cost during your next main phase
As you get more cards, Duelist Points, or just win many times against a single opponent, you will also open up more booster packs to choose from when winning duels
While many players will still choose to build tier decks, the free cards from Golden Packs and the overall decrease in the cost of playing constructed on Arena might free more players to build fun decks or rogue brews since the risk building a deck that isn't successful is much lower since building a second deck should be much cheaper or less time consuming
Personally, just imagining this gets my blood boiling