Yes, person who already knows how to play and is only reading this to pick holes, thats not ideal in competitive play, but hush up, its perfect when figuring it out for yourself
Oh, how it becomes worse with each time you cast one, and oh, how putting the copies on the bottom of your library makes it harder to do each time
Then for each blight counter on it, each opponent loses 4 life unless that player sacrifices a nonland permanent of their choice or discards a card
Toss in the fact that Thalia, Guardian of Thraben already has several printings including a WMCQ Promo with unique art and I'd guess that the pricing of the different versions of Thalia, Guardian of Thraben will look much like the pricing of the different Secret Lair printings of Serum Visions with the one with the most desirable art being slightly more valuable than the rest, but the total value ending up right in the $30 or $35 range