The decklist provided is a typical The Ur-Dragon build, with a mix of generic typal support and more specific dragons-matter cards
And since the deck only plays 22 lands, casting a Disintegration will often take your entire turn
Given that rule, the legality for each event would be as follows: Sets 1 3 Legal May 25th 26th Atlanta, Georgia May 25th 26th Lille, France Sets 1 4 Legal Ursulas Return retail release May 31st June 8th 9th Chicago, Illinois July 6th -7th Bochum, Germany July 20th 21st Fort Worth, Texas August 3rd 4th Bologna, Italy August 24th 25th Toronto, Ontario Sets 1 5 Legal Set 5 retail release August 23rd September 21st 22nd Las Vegas, Nevada September 21st 22nd Birmingham, UK October 26th 27th Seattle, Washington Why Isnt Ursulas Return Legal Straight Away
It current price is around $0.72
Fantastic Four These are the only officially confirmed Commanders from the set so far, having been revealed as part of the set preview
But maybe that makes it unique enough in decks that aren't running green