Rivals of Ixalan

Tetzimoc, Primal Death | Legendary Creature | Elder Dinosaur | Deathtouch {B}, Reveal Tetzimoc, Primal Death from your hand: Put a prey counter on target creature. Activate only during your turn. When Tetzimoc enters the battlefield, destroy each creature your opponents control with a prey counter on it. | Zack Stella

Etali, Primal Storm | Legendary Creature | Elder Dinosaur | Whenever Etali, Primal Storm attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs. | Raymond Swanland