Any of these makes an excellent first box
If you can't, sacrifice this artifact
Come on, people, lets move: Getting Challenger +2 on all of your characters when Lilo is played is great, but youll want to pull her later on in the turn order to make sure you have enough characters on the board to make it worthwhile
Dragons of Tarkir gave us five newcomers (Dragonlord Silumgar, Dragonlord Atarka, etc.), Core Set 2019 gave us retrains of the originals (Arcades, the Strategist, Nicol Bolas, the Ravager), Strixhaven added five more as the namesakes of the different schools (Tanazir Quandrix, Beledros Witherbloom, etc.), and the five metal dragons from Baldur's Gate were also given the double creature type (Ancient Bronze Dragon, Ancient Copper Dragon, etc.)
With a Winter Orb or Stasis in play, you can attack with a small flier and untap your own land, giving you access to mana while everyone else is frozen
The Celestus helps you take advantage of the day and night cycle, which youll be involved with anyway