It lets you play an entire curve of creatures without having to pay for them or find colored mana, and it lets you do it as an instant through any amount of counter magic
But knowing the correct dimensions for standard and jumbo Pokmon cards can be useful for spotting fakes, avoiding cheaters, and buying sleeves and binders to protect your collection
Until the end of the turn you can then play that card - if you dont, it stays exiled
There are also some number of quality utility lands that involve sacrificing that make this card even better: favorite Mirrorpool springs to mind, but theres also Buried Ruin, Command Beacon, Inventors Fair, Urzas Saga, and if youre a degenerate Strip Mine
Victini is your Klinklang counter while Mewtwo is useful in Knocking Out Deoxys- EX , who will become very prominent in the format
Ultra Rares can be identified by their rarity set symbol, which is a double white/silver star on the bottom left-hand corner of the card