Maelstrom Pulse, while a bit expensive, seems like a fine one-of or so in Golgari decks, and is a nice way of shutting down a fast aggro draw or getting rid of multiple Unholy Annexes
The location itself works well with King or Prince characters, lowering the cost of your other characters by one when you have a royal on the rock
In the game, the event debuts Pikachu wearing a Pokmon TCG hat as well as Pokmon that are featured in the card expansion appearing in the wild and in raids
I think this is a bit narrow to dissuade snow lands, especially in older formats
Formats are just faster than they once were, and these slow, painful cards become especially punishing when you're facing down faster, more aggressive cards from your opponent