A Turn 1 Dryad Arbor isn't really any different from a Turn 1 Llanowar Elves or Elvish Mystic, and while this is true on Turn 1, the big difference is that Green Sun's Zenith is both a Llanowar Elves on Turn 1 and a Primeval Titan on Turn 5 or 6 (depending on how much you ramp)
Three years after it was first released as a Secret Lair drop, The Walking Dead cards are finally getting Universes Within reprints
There is some counterplay in the format however, and in specific Teferi, Time Raveler often punishes people who bring in Veil of Summer against blue decks, since you will not be able to respond to any spell anymore
That's why she's barely better than her planeswalker buddy
A creature attacks alone if it's the only creature declared as an attacker during the declare attackers step (including creatures controlled by your teammates, if applicable)
The defending player chooses and sacrifices the required number of permanents before they declare blockers