This mechanic has been so effective that weve actually seen fewer transformation mechanics and seen sets with as few as one Transform card to tell a story (Nicol Bolas, the Ravager in M19)
While we already saw the power of Thalia in powered formats, where she can hate out combo decks and slow down sweepers, such as in the Five-Color Humans deck above, the card has also enjoyed a great deal of success as just a good card for aggressive, creature-heavy decks. Creatures (27) 3 Fiend Hunter 4 Champion of the Parish 3 Avacyn's Pilgrim 3 Mayor of Avabruck 3 Thalia, Guardian of Thraben 2 Restoration Angel 3 Sigarda, Host of Herons 4 Silverblade Paladin 2 Druid's Familiar Lands (25) Spells (8) While Thalias ability is so good, she would likely see a fair bit of play even without first strike, its actually the first strike that really gets her over the finish line
Its even a knight, for what its worth
1 Bloodhusk Ritualist
Time Twister $16,800 Yet another card that seems fair at first glance, if you dont have a very solid understanding of the game mechanics behind it