Mystic Sanctuary
Especially if you can ramp to these on turn 3, theyll provide an incredible defense until they grow to game-winning size (also try giving them evasion with cards like Temperamental Oozewagg or Meteoric Mace)
Starter 20 has multiple strong Big Mom Pirates cards, like 1-cost Charlotte Pudding, 5-cost Charlotte Katakuri, and 6-cost Charlotte Linlin
One of the more interesting features of this set is going to be seeing how they work in the four elements from Avatar: The Last Airbender, air, earth, fire, and water, and make them match up with Magic's five-color system
It's probably the hardest zone to wrap your head around, so I'd recommend further reading
Still, I went 4-1 in both Leagues, beating multiple Grixis Deaths Shadow lists, multiples of Mono-Green Tron, multiple blue control decks, and even an Izzet Phoenix for good measure