Aurora makes for a reliable one-cost card , which is crucial for the start of any game, and perfect for a Princess-heavy deck
When thats paid, the rules text for adapt takes over: If this creature has no +1/+1 counters on it, put a +1/+1 counter on it. When the cost is paid and the ability resolves, theres a check if there are +1/+1 counters on the car d
The mana cost of this card will make most skeptical
These cards use loyalty counters and activated abilities that can swing games dramatically
And even though your creatures look identical, yours actually has the quite relevant "ability" of being an Elf
Considering that the winning decklist in Premodern was a land destruction one based on Wasteland and Armageddon, Terravores price spike may begin to make a bit more sense