That something is usually: a cost (example: Sacrifice a creature: [effect]), or an effect (example: Target player sacrifices a creature.) No instruction, no sacrifice
The only thing Kroxa needs is a deck full of other cards that can reliably keep the graveyard full
When you buy a PSA-graded card, you know youre getting a genuine item whose condition has been professionally verified
But having to commit to casting a four-drop every turn can tie up a lot of mana, so you need to be smart about your plays and maximize your attacks
You have so many different creatures at your disposal, and most will come with some sort of mechanics attached, such as Reach, Vigilance, Deathtouch, Menace, or Trample, while others are token generators
Kaito, Cunning Infiltrator has a lot going on for a three-mana walker