Ral Zarek is most comparable to Ajani Vengeant, who is arguably the third best planeswalker ever after Jace, the Mind Sculptor and Elspeth, Knight-Errant
You can either choose to deal three damage to each creature and each planeswalker, or you can destroy all artifacts with a mana value of three or less
a little more durdly and janky, if you like
Three mana to reanimate two small creatures is a pretty good deal, but how often will you have stuff in the graveyard to get back
While Unholy Heat is certainly an excellent Magic card, and is one of the most efficient removal spells ever printed, its the only card in the Top 9 that can be easily replaced
You can obtain the Clefable (1-Star Shiny rarity) card by opening Fantastical Parade from Fantastical Parade set