While she doesnt cheat out Dragons quite as well as Ur-Dragon, she doubles them up, and that means you get all their ETBs and static effects twice
There simply hasnt been enough support for Planeswalkers over the years for that type of deck to consistently succeed
As such, it lends itself very well to deck upgrades, but even if you forgo upgrading it, Limit Break is still a great deck to play with out of the box without any alterations
Legendary power, protected and ready to open
From hard stax pieces like Elesh Norn, Mother of Machines, Drannith Magistrate, and Archon of Emeria to softer disruption in Thalia, Guardian of Thraben or Ranger-Captain of Eos, white disrupts and stops your opponents better than any color except maybe blue and its countermagic
If you have no other action going on and a bunch of cantrips, you can wait until you have an open mana to cycle a cantrip and get a Monk token