All in all, I think Volatile Stormdrake will not only be a great budget replacement for the Reserved List-bound card, it will be one of the first cards of that description that might as well be the same thing
It's very popular for Commander players to include three or more colors in their decks, so only having access to black mana is a huge problem
If Deadpool took the Textbox of Alexios, even though Deadpool's name would not change, it would gain all of the abilities that affect Alexios
You can call it canon at any time because thats what the multiverse implies, but at the same time those promotional cards were just card styles and not actual standalone cards like the Street Fighter or Walking Dead Secret Lairs
If you prefer to play in formats such as Standard or Alchemy, it is not recommended to spend wildcards on spells that will soon be taken out of rotation
The sky is the limit with Xenagos, The Reveler, and the amount of all-around value that comes from the card makes it easily the best Gruul planeswalker out there.