Legendary Creature — Elder Dinosaur
Whenever Etali 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.
6/6

Big red-friendly creature with multiple free cascades for chained spells.

Cascade twice plus haste, similar free-spell payoff.

Red impulse value engine casting off the top of libraries.

Lets you cast spells from the top of your library for free-ish.

Big creatures like Etali trigger damage payoffs.

Doubles Etali's power and grants haste for huge attacks.

Extra combat steps retrigger Etali's attack ability.