They will hit the graveyard, trigger dies abilities, then cease to exist shortly after
Later Magic sets (such as Vintage Masters seen in the Force of Will example above), have both the collectors number , set code , and rarity in the lower lefthand corner of the card
Its especially powerful in EDH with multiple players casting multiple spells a turn
The Mew name keeps a floor under it
Tundra Wall is no joke for competitive players, either, granting a solid protection to Pokemon with Basic water energy attached, while Freezing Chill shuts off your opponents Pokemon from attacking altogether.
Mutating a creature onto Ivy turns it into a token copy, giving you all sorts of potential for shenanigans, especially if you play a few copy spells and choose to make Ivy nonlengendary by placing the mutate creature on top of Ivy