The first edition Charizard is recognized as the most valuable playable Pokmon card, and Presentation Blastoise is noted for its rarity and historical significance
People just do not expect a counterspell from someone playing non-blue colors, and even though this card only provides a temporary solution (the countered spell goes atop your foes library instead of the graveyard), this can still save you from near-certain death in the right scenarios
As such, it's easy to find a way to return Thousand-Faced Shadow to hand so that it can copy another attacking creature later on
These include cards like Adorned Pouncer (double strike, eternalize), Cubwarden (lifelink, creature tokens), Felidar Sovereign (vigilance, lifelink, win con), Jinnie Fay (creature tokens), Kaheera (anthem effect), Loyal Warhound (ramp), and many many more