This is one of the first decks I built, and still one of my favorites. It's been updated along the way, but the core is still base set Xyx beat down. Delia starts, abusing Vellups to delay your opponent, and hopefully take out at least one magi. She's got eternal vellups, mixed with Elders occasionally, who can get you your Xyx's, or Flutteryups.
After Delia gets taken out, bring out Lady of the Sky, and (hopefully) play 3 Xyx minors, a Xyx or two, or some spells as needed. Immediately boost your Xyx minors up - they'll have 4 energy each, so you can use each's abilities. If you need a huge target, put one up to 14. Otherwise just grow them up by 2 each, or boost a Xyx to kill a magi. Cry of Thunder is also exceptionally useful.
Sorreah can really be swapped out with a lot of different magi - you're counting on Ora to finish off two magi. If you get to Sorreah, hopefully a couple well placed spells will finish off a final magi, giving you the win.