When it was printed it was heavily played in kitchen table formats like early Commander and Five Color that dominated the format with their good answer to anything save for a black dork
Its just a great card as an imposing threat that doesnt go away without an exile effect
Summon: Fat Chocobo is the exception, as it just puts tons of stats on the board, but most 3-5 mana threats arent really what this deck is looking for
The object of the game is to summon all manner of Disney heroes and villains using ink as a resource, and then race to see who can accumulate 20 lore first
What set is Regeneration from
Do note, however, that if youre going to be picking up the Introduction to Evil set in order to get hold of this card, that itll need to have the Lorcana promo sticker on the packaging, as shown in the above image