Simply put, you can blow up anything at instant speed for just four mana
After weeks of being upwards of $70 each (with the exception of Final Fantasy 6s Revival Trance, which has always hovered close to MSRP), you can now buy a bundle of all four decks for $200 (or $199.99, to be precise)
if they haven't gotten there yet, it's going to be very, very difficult to make a legit run for the Top 8
The Dungeon mechanic and the d20-rolling mechanic both return, for instance
In casual play, it could also still be easy to take advantage of its significant power, although it's only fair to do so if both parties are on board with using a card that's been errata'd for a reason
Alseid of Life's Bounty and Healer's Hawk are great 1-drops that synergize with everything, while The Birth of Meletis is a very interesting new card that is a Wall of Omens variant with lifegain applications as well