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

Form of the Dinosaur | Enchantment | | When Form of the Dinosaur enters the battlefield, your life total becomes 15. At the beginning of your upkeep, Form of the Dinosaur deals 15 damage to target creature an opponent controls and that creature deals damage equal to its power to you. | Daarken